ML239 is a potent and selective inhibitor of breast cancer stem cells, with an IC₅₀ of 1.16 μM. In Vitro: ML239 (Compound 7j) is a potent and selective inhibitor of breast cancer stem cells, with an IC₅₀ of 1.16 μM, with ∼24-fold selectivity against the control cell line^[1]. ML239 inhibits breast cancer stem-like cells, most likely through activation of fatty acid desaturase 2 (FADS2). ML239 is cytotoxic to NCIH661 cells, and FADS2 knockdown reduces ML239 cytotoxicity, and furthermore, FADS2 inhibitor SC-26196 also reduces ML239 cytotoxicity in cancer cell lines (CCLs)^[2].