GFP expression in Kit⁺ fetal liver and yolk sac cells. (A-B) FACS analysis of GFP and Kit fluorescence in fetal liver cells at E11.5. (A) Construct 3. (B) Construct 2. (Ai,Bi) Second antibody; (Aii,Bii) first and second antibodies. (C) GFP (green; Ci) and Kit (red; Cii) fluorescence in E9.5 yolk sac cells. No expression is seen with construct 1. Original magnification, × 400.