MAPKKKs phosphorylate and activate MAPKKs, which further phosphorylate and activate MAPKs.198 It has been demonstrated that ERK1/2, p38, and JNK MAPK are activated and increased in psoriatic lesions, indicating that the MAPK pathway is involved in the pathogenesis of psoriasis.199–201. The gene discussed is MAPK3; the disease is psoriasis.