Non-calcium-dependent contraction pathways, showing both thick and thin filament regulation. PKC, protein kinase C, basal activity (117); PKCε abundance (30); MAPK, mitogen activated protein kinase; ERK1/2, extracellular regulated kinase abundance (100); Phosphorylated ERK1/2 (70); ERK1/2 negative feedback on PKC (significantly greater); Rho A abundance (100); CPI-17 (significantly less). (Numbers in parentheses represent fetal values, as percent of those of adult).