ALDH1A1 and non-small cell lung carcinoma: EGFR TKI treatment increased the population of CSCs in EGFR-mutated NSCLC, and CSC-related markers, such as CD44, CD133, integrin α6, Oct4, Sox2, Nanog, and ALDH1, were highly expressed in patients with EGFR-TKI-resistant NSCLC [33,34].