ALDH1A1 and glioblastoma: ALDH1A3 activity on human glioblastoma U87MG and colorectal HCT116 cancer cell lines was investigated by transiently transfecting them with shALDH1A3 and comparing the results with negative controls (HEK293T positive to ALDH1A2, hASTRO and CCD-8Co positive to ALDH1A1 and 4T1 negative to ALDH1A subfamily).