COL9A3 and breast cancer: The most substantial gains in ESR1-depleted tumors are genes generally expressed in basal breast cancers—such as NDRG1, DKK1, KIT, KLK7, PROM1, and COL9A3—and genes significantly lost in the ESR1-depleted subset are generally downregulated in basal cancers—EVLOVL2, BCL2, IGF1R, MYB, RABEP, and ATP8A2 (MsigDB: SMID_BREAST_CANCER_BASAL_DN/UP gene lists) [74].