JMJD6 and neoplasm: In agreement with the observation, immunohistochemical staining of Ki-67, a well-documented marker for cellular proliferation, in xenograft tumor section demonstrated that JMJD6-depleted HCT116 p53+/+ xenografts exhibited substantially fewer Ki-67–positive nuclei than HCT116 p53+/+ xenografts without JMJD6 depletion, whereas HCT116 p53−/− xenografts displayed no difference in population of Ki-67–positive cells when cells were infected with either control siRNA or JMJD6 siRNAs (Figure 4F).