We used the following previously characterized pairs: RB1-wt PC3 and RB1-mutant DU145 prostate cancer cells, RB1-wt U2OS and RB1-mutant Saos-2 osteosarcoma cells, and RB1-wt MDA-MB-231 and RB1-mutant MDA-MB-468 triple negative breast cancer cells [11,54–58]. The gene discussed is RB1; the disease is osteosarcoma.