Flow cytometry analysis of αHER2-eStcE-treated animals revealed a modest but significant reduction of cell-surface mucins on EMT6HER2 cancer cells (CD45–HER2+ cells) without affecting mucin levels on immune cells (CD45+HER2– cells), suggesting that αHER2-eStcE promotes selective mucin depletion in vivo (Extended Data Fig. 10e,fand Supplementary Fig. 11). Here, MUC5AC is linked to cancer.