Our study demonstrated that in JAK2V617F cMPNs, Dnmt3a positively regulates the expression of Cdkn1a, which induces G0/G1 cell cycle arrest, indicating that Dnmt3a also serves as a tumor suppressor in cMPNs by regulating the cell cycle through Cdkn1a, which in turn affects the proliferative capacity of Jak2V617F BaF3 cells. The gene discussed is CDKN1A; the disease is neoplasm.