BCL2 and essential thrombocythemia: In the MPN pathophysiology, they reported dysregulation of the intrinsic pathway in apoptosis activation, namely, they observed increased expression of anti-apoptotic genes A1, BCL-2, BCL-XL, and BCL-W in leukocytes of ET and PMF patients, and decreased expression of pro-apoptotic BID and BIMEL genes in leukocytes of ET patients (Table 2).