KDM6A and breast cancer: We derived stable Kdm6a-targeted ES cell clones from both BC and CB crosses by inducing either a deletion between exons 2 and 4 (ΔE) or a deletion of exons 1 and 2 in the promoter region (ΔP) (Fig. 1A and Additional file 1: Fig. S1A-D and Additional file 8: Table S8A).