BMI1 and squamous cell carcinoma: PTC209, a potent and selective BMI1 inhibitor, effectively reduces BMI1 expression and demonstrates robust anti-tumor activity against various cancer cell types, including biliary tract cancer, acute myeloid leukemia, glioblastoma, myeloma, squamous cell carcinoma, and colon, breast, and lung cancers [[4], [5], [6], [7], [8], [9], [10]].