Inhibition of p38-MAPK and activation of JNKs were tested for effects on the level of S-phase entry that could be induced by rhGGF2. In the presence of rhGGF2, treatments with the p38-MAPK inhibitor SB203580 at 10 μm resulted in a reduced average incidence of S-phase labeling, but this effect was not significant when compared with the level of entry obtained with rhGGF2 alone. In contrast, treatments with 10 ng/ml anisomycin (Aniso), an activator of JNKs, significantly reduced the level of S-phase entry in the presence of rhGGF2.