To test for a tumor-intrinsic role for ALDH1A3, we generated two independent CRISPR-Cas9 knockouts of ALDH1A3 in the cell lines with high endogenous ALDH1A3 activity: MDA-MB-468 (triple-negative breast cancer), A375 (melanoma), and LN229 (glioblastoma). The gene discussed is ALDH1A3; the disease is triple-negative breast carcinoma.