MAPK3 and renal cell carcinoma: In all three RCC cell lines the selective ERK inhibitor PD98059 (treatment 72 hrs) led to dose-dependent reductions in pERK-1/2 (Figure 5A) and decreases in cell proliferation (Figure 5B) but had no effect upon Cav-1 expression (Figure 5A), indicating Cav-1 is not serving as an immediate downstream effector molecule of ERK-1/2.