JAK2 and myeloproliferative disorder: The dysregulation of apoptosis in MPN is a general phenomenon, due to constitutive activation of JAK2/STAT, PI3K/AKT and Ras-MAPK/ERK signaling pathways, given that STAT transcription factors modulate the expression of proteins involved in apoptosis, such as c-Myc, cyclin D, MCL-1 and BCL-XL [19,64,65].