ALDH1A1 and lung carcinoma: Targeting ALDH proteins is one of the potential approaches to combat CSC chemo- and radio-resistance [99]: pre-incubation of lung cancer cell lines with all-trans RA decreases the expression level and the enzymatic activity of ALDH1A1 and ALDH3A1 and makes cancer cells far more sensitive and vulnerable to chemotherapeutic treatments [136].