KRT5 and breast cancer: The use of Trp63CreERT2; Rosa26lox-STOP-lox-tdTomato mice in our scRNA-Seq screen allowed the identification of a broader range of BCs compared with similar screens using Krt5CreER based lines, given previous reports of KRT5 negative cells in the BC pool (Yang et al., 2018; Xi et al., 2017).