Fig 4. Involvement of AKT/ERK/p38 in P4-induced increases in the levels of p21^cip1 and p27^kip1 protein in RASMCs.

(A) Pre-transfection of RASMCs with dn-ERK2 cDNA prevented P4-induced increases in the levels of p-ERK1/2, and p-p38 protein, but not p-Raf-1 and p-AKT protein. (B) Pre-transfection of RASMCs with dn-AKT cDNA prevented P4-induced increases in the levels of p-AKT, pERK1/2, and p-p38 protein. (C) Pre-treatment of RASMCs with a p38 inhibitor, SB 203580 (1 μM), for 1 h prevented P4-induced increases in the level of p-p38 protein, but not p-AKT and p-ERK1/2 protein. Data are representative of 2 independent experiments with similar results. Values shown in parentheses represent the quantified results adjusted with their own total protein level and expressed as ratio over control. Con, control; dn, dominate negative; SB, SB 203580.