MDM2 and breast cancer: Interestingly, the depletion of RRS1 resulted in an increase in the nucleoplasmic accumulation of both RPL5 and RPL11.21 RPL5 and RPL11 activate p53 by down‐regulating MDM2 in the nucleoplasm.38 MDM2, an E3 ubiquitin, inhibits the activity of p53 through proteasome‐mediated degradation.39 The results of this study indicated that RRS1 knockdown caused a marked increase in ribosome‐free RPL11 levels and a consequential reduction in ribosomal RPL11 levels in breast cancer cells.