BMI1 and uterine carcinosarcoma: Studies using the CS99 cell line, which is derived from uterine carcinosarcomas, showed that inhibition of BMI1 (BMI1 proto-oncogene, polycomb ring finger) with the BMI1 inhibitor, PTC-028, led to increased apoptosis and decreased cell viability in vitro and delayed tumor growth in vivo [43].