JAK2 activation results in the phosphorylation and activation of STAT1alpha, STAT3, STAT5A and STAT5B (Deberry et al. 1997, Brizzi et al. 1999, Ning et al. 2001, Ronnstrand 2004). STAT family members can be activated by JAK kinases, receptor tyrosine kinases or SFKs. LYN kinase has been identified to have role in SCF-induced phosphorylation of STAT3 (Shivakrupa & Linnekin 2005).