K., K. inhibits myosin targeting. We find that by inhibiting the myosin phosphatase, Empagliflozin ERK and RSK promote myosin IICmediated tension for lamella growth and optimal edge dynamics for cell migration. These findings suggest that ERK activity can coordinately amplify both protrusive and contractile forces for optimal cell motility. = 0.03) and RSK inhibition (pattern, = 0.10), but not AKT or Empagliflozin S6K inhibition (Fig. 1= 4 biological replicates for pMYPT1 Ser-668, and = 3 biological replicates for pMYPT1 S507. and is vacant vector control transfection. HA-WT and HA-S507A are HA-tagged WT and S507A mutant transfections, respectively. pMYPT1 S507/HA is usually relative to the signal in the HA-WT starved condition. = 3 biological replicates each. Endogenous phospho-MYPT1 is not detected in the vector transfection conditions because of the reduced intensity used Empagliflozin to scan the overexpressed HA-MYPT1 Western blots. and = 3 biological replicates. One lane of irrelevant treatment condition uniformly removed from for Western blotting quantifications indicate S.D. The pathway agonists are: EGF, insulin (is usually p-RSKT359,S363. is usually p-AKT Ser-473. One-way ANOVA was used. *, 0.05; **, 0.01; ***, 0.001; 0.05); = 0.03) that was reduced with MEK inhibition (= 0.02), trended lower with RSK inhibition (= 0.5), and completely abrogated with the S507A mutant ( 0.002), confirming its specificity. Previous studies in insulin-sensitive cell models suggest that AKT and/or S6K may contribute to MYPT1 Ser-507 in some cases (46, 47). Our results suggest that MEK may additionally signal to MYPT1 Ser-507 impartial of RSK, because MEK inhibitors more completely blocked MYPT1 Ser-507 phosphorylation than RSK inhibitors (Fig. 1, and = 0.00003), and the MEK inhibitor U0126 completely blocked the induction (= 0.00004; Fig. 1= 0.01), and in this case, the phosphorylation was sensitive to the RSK inhibitor BI-D1870 (= 0.03) and a structurally distinct RSK inhibitor LHJ685 (= 0.03; Fig. 1= 0.6; Fig. 1RSK1 + PMA, = 0.07; and RSK2 + PMA, = 0.02; RSK2 + no stimulation RSK2 + PMA, = 0.008; Fig. 2and = 0.04; pattern for RSK1-37, = 0.3; RSK2-65, = 0.0002; and RSK2-70, = 0.01; Fig. 2= 5 biological replicates. indicate S.D. Endogenous phospho-RSK is not detected in the vector control because of the reduced intensity used to scan Western blots with overexpressed HA-RSK. and = 3 biological replicates. indicate S.D. RSK/GAPDH signal is usually relative to that in the nontargeting control CRISPR (= 3 biological replicates. indicate S.E. with four technical replicates per experiment. = 3 biological replicates. indicate S.D. 0.05; **, 0.01; ***, 0.001; 0.05). RSK activity is usually reported to be necessary and sufficient for cell migration, based on studies with RSK inhibitors SL0101, FMK, Emr1 and BI-D1870 and constitutively active RSK1 and RSK2 Empagliflozin in HeLa, MCF10a mammary epithelial, and WM35 melanoma cells (58, 61, 62). However, a conflicting report with RSK1 siRNA suggests that RSK1 inhibits migration in nonsmall cell lung cancer cells, including A549 cells Empagliflozin (60). We sought to determine whether overall RSK activity promotes or inhibits migration using a random-walk assay with the migratory Cos7 and A549 cell lines. We manually tracked the migration paths over 4C6 h and calculated velocity (average displacement for a 10-min time interval) and persistence (ratio of displacement to trajectory length). As expected, MEK inhibition with AZD6244 reduced migration velocity and path length (Fig. 3, = 1.8E-11 and = 1.5E-15, two-sample nonparametric KolmogorovCSmirnov test; Fig. 3= 2.8E-10 and = 3.1E-9; Fig. 3Cos7 and A549 cells treated with DMSO, MEK inhibitor AZD6244 (span the 25th to 75th distribution. The indicates the median for all those cells. indicate 95% CI around the median. values in show samples with distributions distinct from the control DMSO condition, from KolmogorovCSmirnov test. show S.E. and and 0.05, KolmogorovCSmirnov test; Fig. 4, and show region of interest that protrudes in later frames. The shows protrusive region. significant protrusion events in = 6 cells treated with DMSO, 5 cells with AZD6244 (span the 25th to 75th distribution. The indicates the median. Notches are 95% CI of median. Samples with distributions distinct from control have values labeled in value from KolmogorovCSmirnov test. Inhibitors are the MEK inhibitor AZD6244 and the RSK inhibitor BI-D1870..