Since previous oncological studies had shown a strong correlation between MUC1 expression and abundant mast cell infiltration in the context of renal and breast cancer, and considering the finding of increasing MUC1 in severe forms of CRSwNP, we expected to observe a colocalization of mast cells with MUC1 in nasal polyps as well [27,28]. The gene discussed is MUC1; the disease is breast cancer.