RB1 and pituitary tumor: We did not investigate in detail other phenotypes previously described in RB deficient adult mice, such as liver steatosis or adrenal gland tumors [37], but the time frame of death from pituitary tumor development in shRb mice when dox treatment is started in young adults is strikingly similar to what has been observed upon Rb deletion specifically in the pituitary gland at early stages of development [43], indicating that the inducible knock-down approach is highly effective.