Based on relevant morphogenesis and correct polarization as recorded by expression in luminal epithelial cells of mucin 1 (Muc1), occludin, and keratin 19 (K19) and expression in basal cells of integrin β4, p63, and K14, non-malignant organoids were present in all primary human breast cancer-derived cultures. Here, KRT19 is linked to breast carcinoma.