In proliferative human VSMCs, miR-638 expression was decreased and both SMC proliferation and migration in response to PDGF stimulation were suppressed. PDGF-AA inhibited miRlet-7d, while PDGF-BB induced miR-146b in cancer cells. The induction of miR-146b by PDGF-BB is regulated via MAPK-dependent induction of c-fos. This evidence concerns the gene FOS and cancer.