MUC5AC and breast cancer: Furthermore, cells showed positive IF signals for KRT17-, KRT5-, p63-, AcTub-, MUC5AC-, MUC5B-, and MMP7 as presented in Fig. 5E and quantified in Fig. 5F. Polarized lumen were present in approximately 40% of the organoids after 21 days, with BC (KRT5+, KRT17+, p63+) mainly located at the outer layer, and ciliated (AcTub+)-, secretory (SCGB1A1+, MUC5AC+, MUC5B+)-, or MMP7+epithelial cells at the luminal site of the organoids.