SOX9 and breast carcinoma: However, these observations do not eliminate the possibility that LATS1/2 inactivation in ER+ luminal cells drives plasticity to a Sox9+ basal-like state as well, as the K8CreERT2 model we used efficiently targets both Sca1+ and Sca1− luminal mammary epithelial cells48, and we observe strong repression of Esr1 and Pgr in lineage-traced cells isolated from Lats1/2f/f; lsl-EYFP; K8CreERT2 mammary carcinomas.