We previously found that systemic (germline) genetic deletion of p38δ inhibited DMBA/TPA-induced skin tumorigenesis via attenuation of the proliferative ERK1/2-AP1 pathway and suppressed K-Ras-driven lung tumorigenesis, indicating a tumor-promoting function for p38δ in skin and lung tissue in vivo [11]. This evidence concerns the gene MAPK3 and neoplasm.