SKP2 and retinoblastoma: RB1 loss was also associated with robust sensitivity to SKP2, a binding partner of Rb (Ji et al., 2004) first identified as an RB1 synthetic lethal partner in retinoblastoma (Xu et al., 2014) and more recently as a highly penetrant RB1 synthetic lethal partner in triple negative breast cancer (Brough et al., 2018; Figure 4C and D).