CYP19A1 and neoplasm: When combined with all-trans retinoic acid (ATRA) and doxorubicin, Ent improved the retinoic acid-mediated differentiation by inducing retinoid acid receptor expression and also enhanced doxorubicin-driven cytotoxicity; and Ent combined with ATRA also helped overcome aromatase inhibitor (AI) resistance by reducing the tumor-initiating cell population (Schech A. J. et al., 2015; Merino et al., 2016).