RPS15 and cancer: Bypassing this QC step (through the unregulated release of Enp1 with the Enp1_R333E mutation, deletion of an internal loop in Tsr1, Tsr1_Δloop, or a cancer-associated mutation in Rps15, Rps15_S136F) impairs start codon selection (Fig. 3 B; Huang et al., 2020), as expected from weakening the stability of the scanning complex.