“…Given the dependency of such tumors on ribosome biogenesis (Barna et al , ; van Riggelen et al , ), a search for novel agents that specifically target this process has been initiated (Bywater et al , ; Pelletier et al , ). Importantly, insults to ribosome biogenesis, including c‐Myc‐induced oncogenic stress (Macias et al , ; Morcelle et al , ), also trigger a p53‐mediated cell‐cycle checkpoint, recently termed the impaired ribosome biogenesis checkpoint (IRBC) (Gentilella et al , ; Pelletier et al , ). The IRBC is mediated by a nascent pre‐ribosomal complex containing RPL5 (or uL18), RPL11 (or uL5), and 5S rRNA, which upon insults to ribosome biogenesis, is redirected from its assembly into 60S ribosomes to the binding and inhibition of the p53‐E3‐ubiquitin ligase HDM2 (or MDM2) (Donati et al , ), leading to p53 stabilization (Kubbutat et al , ; Pelletier et al , ).…”