It was reported that extracellular signal-regulated kinase (ERK1/2) phosphorylation is a crucial signaling pathway in the differentiation of mesenchymal stem cells and acute myeloid leukemia [26, 27], we sought to investigate the association between ERK1/2 signaling and let-7b expression in psoriasis development. The gene discussed is MAPK3; the disease is acute myeloid leukemia.