Altogether, the overexpression of JAK2 and STAT3 in CLL cells, the phosphorylation, and the nuclear localization of P-STAT3 Tyr705 at basal condition, suggest that JAK2/STAT3 pathway is constitutively active in CLL and might play a key role in its pathogenesis and growth. The gene discussed is STAT3; the disease is B-cell chronic lymphocytic leukemia.