PIK3CD is a bona fide RUNX1 target gene in AMkL. (A-C) In vivo binding of RUNX1 to the putative RUNX1 binding sites located in the upstream region of the PIK3CD gene (A) in Meg-01 cells was determined by ChIP assays with the use of regular PCR (B) and real-time PCR (C), as described in “Methods.” (D-E) KA1b cells were transfected with pGL3Basic-PIK3CDpro along with pRLSV40 by electroporation. The transfected cells were split into 2 equal aliquots with 1 induced by 2 μg/mL Dox. Cells were harvested 24 hours after transfection, and induction of RUNX1b was determined by Western blotting (D) and luciferase activities were assayed (E) as described in “Methods.” **Statistically significant differences (P < .005). (C and E) Error bars indicate SEs.