JAK2V617F and TET2KD cooperatively drive cell proliferation. (A) Percentage of immunohistochemically Ki-67-positive myeloid cells in BM. TET2KD mice and JAK2V617F mice showed increased Ki-67 positivity relative to WT mice. Double-mutant mice showed significantly increased positivity relative to single-mutant mice. (B) Percentage of immunohistochemically Ki-67-positive cells in spleen. The pattern of results is similar to that observed in BM. Error bars represent standard deviation. *P < .05 and **P < .01 vs WT mice; †P < .05 vs JAK2V617F mice. (C) Representative immunohistochemical staining for Ki-67 in BM and spleen of recipients.