Figure 4. RSK functions as a Ca²⁺ independent kinase to increase force and RLC₂₀ phosphorylation.

RSK inhibition increases the time to the onset of force and the rate of force development (t1/2) induced by the MLCP (PP1C) inhibitor microcystin-LR (10 µM) in the absence of Ca²⁺(pCa 9.0) The relative phosphorylation of RLC₂₀, measured at 25 min following the addition of microcystin, was decreased in the presence of BI-D1870 (1 µM).