Subsequent Western blot analysis of these leukemias demonstrated sustained depletion of Jak2 (Fig. 3J, lanes M4–M7), and a decrease in pStat5Y694 was observed in dsRed+ Eμ-Crlf2/Jak2P933R-pREBIR-shJak2.3323 leukemia cells harvested from moribund Dox-treated mice (Supplemental Fig. S3B,C). Here, CRLF2 is linked to leukemia.