CREB3L1 and breast cancer: To assess the utility of these drugs across additional CREB3L1-deficient breast cancer cells, we evaluated the cytotoxicity of palbociclib isethionate, cladribine, lanatoside C and homoharringtonine across a panel of CREB3L1-deficient TNBC cell lines, including BT549, HCC1395, HCC38, Hs578T, MDA-MB-157 and MDA-MB-436 (Table 2).