MUC1 is a heterodimeric transmembrane glycoprotein that functions as a multifaceted regulator of cell signaling and gene expression 1. The MUC1-C beta subunit contains a C-terminal domain mediating phosphorylation-dependent signaling through ERK, SRC, and NF-κB pathways, with particular relevance to TP53-mediated transcriptional regulation 2. In normal tissues, MUC1 is expressed on apical surfaces of polarized epithelial cells in the kidney, oral mucosa, and salivary glands, where it provides mucosal protection and facilitates epithelial integrity 3. In cancer, aberrantly glycosylated and overexpressed MUC1 promotes tumor progression through multiple mechanisms: it activates polycomb repressive complexes (PRC2 and PRC1) by driving EZH2 and BMI1 expression, leading to repression of tumor suppressors including CDH1, CDKN2A, PTEN, and BRCA1 4. MUC1 overexpression is associated with epithelial-mesenchymal transition, cancer stem cell characteristics, and drug resistance across breast, stomach, lung, and genitourinary cancers 56. MUC1 mutations cause tubulointerstitial kidney disease, autosomal dominant type 2. MUC1 serves as a biomarker for cancer diagnosis and a therapeutic target, with immunotherapy approaches showing promise in breast cancer treatment 5.