Fig 4. ALDH1B1 knock down depletes ALDH^bright cells.

Flow cytometry was conducted in SW480 cells transfected with either ALDH1B1 shRNA or scramble shRNA. Cells were incubated with Aldefluor substrate in the presence or absence of the ALDH inhibitor diethylaminobenzaldehyde (DEAB). Cells with high fluorescence (reflecting high ALDH activity, i.e., ALDH^bright cells) were determined and arbitrarily defined as being in the oval gate in the bottom right quadrant of the graph. (A) Flow cytometric analysis of scramble shRNA control cells in the absence (-DEAB) or presence (+DEAB) of DEAB. (B) Flow cytometric analysis of ALDH1B1 shRNA cells in the absence (-DEAB) or presence (+DEAB) of DEAB; (C) Proportion of ALDH^bright cells in ALDH1B1 shRNA (black bar) and scramble shRNA (white bar) cell populations. Data are presented as the mean ± SEM from 3 experiments. * P < 0.05, Student’s unpaired t-test, compared with scramble shRNA cells.