The shared expression of CK5 and CK14 in adult human, but not mouse, basal and TDLU luminal cells is of particular relevance because TDLUs have been implicated as a frequent physical site of origin of human breast cancers (Gusterson, 2009, Gusterson et al., 2005, Wellings et al., 1975). The gene discussed is KRT5; the disease is breast cancer.