The importance of the status of the p53-pRb-mediated control of cell cycle progression in the cell response to chemotherapeutic agents that hinder ribosome biogenesis was also suggested by a study on the effects of 5-Fluorouracyl (5-FU) and methotrexate treatment on human cancer cell lines, after silencing for RB1 expression. The gene discussed is RB1; the disease is cancer.