MAP3K5 and rhabdomyosarcoma: Indeed, p21 prevents stress-induced apoptosis mediated by the JNK and p38 signaling pathways by binding to and inhibiting the activity of the MAP3K5 (ASK1; MEKK5) in human rhabdomyosarcoma cells [48] and by binding to JNK kinases, further preventing their activation by upstream kinases [49].