Fig. 1. The prostate contains cells with high ALDH activity.

Prostate cell digests were incubated with Aldefluor in the presence (A) or absence (B) of DEAB. (A) Aldefluor substrate plus the inhibitor, DEAB, was used to establish baseline fluorescence (few cells in R1). (B) High levels of ALDH were expressed by ~8% of cells (R1). R2 denotes ALDH lo cells. Phase contrast photographs of cells in the presence (C) and absence (E) of DEAB show small round cells that under fluorescence microscopy exhibit no fluorescence in the presence of inhibitor (D) but bright green fluorescence in the absence of the inhibitor (F). Scale bars = 10 μm.