ALDH1A1 and cancer: The mRNA and protein levels of the cancer stem cell markers DCLK1 and ALDH1A1 remained unchanged in both shHPGD- and shGLI1-knockdown HT-29 and Caco-2 cell-derived colonospheres, even after LTC4 stimulation, compared with their unstimulated counterparts (Fig. 6i–k; Supplementary Fig. S9A–H).