Stk4−/− mice lymphocytes are prone to mis-segregate chromosomes during cell cycle and indicate enhanced levels of aneuploidy, which is likely to cause tumorigenesis.[8] Furthermore, a decrease in the count of T and B cells was reported in stk4 knock-out mice base on defect in pro-apoptotic role of stk4.[9] In addition, STK4 expression was significantly reduced in different B-cell lymphoma such as DLBCL, follicular lymphoma, Burkitt lymphoma, hairy cell leukemia, mantle cell lymphoma, and primary effusion lymphoma. This evidence concerns the gene STK4 and hairy cell leukemia.