Red blood cells efflux PPIX due to expression of ABCG2. (A) Murine peripheral red blood cells were incubated with PPIX, with Ko143 (solid line) or without Ko143 (shaded area) and analyzed for PPIX fluorescence. (B) Murine peripheral red blood cells were incubated with (solid line) or without (shaded area) 2-deoxyglucose and sodium azide and analyzed for PPIX fluorescence.