PIK3CD and acute lymphoblastic leukemia: Further, we performed functional analysis using IKAROS-overexpressed and IKAROS-silenced T-ALL cells to determine the functional importance of IKAROS binding to DNA at the promoters of PIK3CD and PIKFYVE. IKAROS was overexpressed in MOLT4 and CEM cells by transduction of a retrovirus expressing wild-type IKZF1 and an empty vector as a control (Figure 3B).