Isolation of ALDHHi, ALDHLow, side population and non-side population cells from clinical human prostate specimen. Cells isolated from clinical human prostate specimen were stained with either DCV or ALDEFLUOR™ reagent. The ALDHHi cells were detected in the higher fluorescent region (A). ALDHHi population was inhibited with DEAB resulting in no ALDHHi cell detection (B). Side population was gated based upon its absence in the presence of FTC, a specific inhibitor of ABCG2 (C and D).