Unsurprisingly, MLL3 KD in ZR751 cells upregulated expression of MLL4, albeit not to statistical significance, and in TCGA ER+ luminal breast cancer studies MLL3‐mutant cases had significantly higher expression of MLL4 (p = 0.01176938, ANOVA of multivariate linear regression). The gene discussed is KMT2C; the disease is breast carcinoma.