Combined activity of Ikzf1 regulatory elements in lympho-myeloid and neuronal cells. (A) Diagram of the Ik-MC2 construct. (B) GFP reporter expression in PBL subsets of the Ik-MC2 founder lines. The percentage of GFP⁺ myeloid cells (gray bars), T cells (black bars), and B cells (white bars) was determined for each founder line by fluorescence-activated cell sorter (FACS) analysis. (C) GFP expression in the HSC-enriched (LSK) and erythro-myeloid (LK-Lin^–c-Kit⁺Sca-1^–) progenitor populations of the bone marrow. CD34 and Flt3 expression in LSK and LK GFP high (hi) and low (lo) subsets are shown. Thin line histogram represents FACS staining of a reporter or marker negative control. (D) Lateral view of GFP expression in the P0 brain in whole mount. The outline of the brain is shown as a white line. Bright GFP expression is observed in the basal ganglia. No fluorescence was observed in wild-type controls under these conditions. Brackets mark the approximate plane of the frontal section shown in panel E. (E) Schematic view of the section indicating the cortex (COR), caudate putamen (CP), and septum (S) and the area shown in the photograph (box). GFP expression is observed in the caudate putamen. With the exception of scattered cells elsewhere, GFP is not observed in surrounding tissue.