TP53 and gastric cancer: Our study revealed a new mechanism of p53 protein ubiquitination mediated by miR‐769‐5p in cisplatin resistance. As an important apoptosis‐related protein, miR‐769‐5p participates in the apoptosis of GC cells through the RNF20‐NEDD4L‐p53 pathway in the process of induced apoptosis, and miR‐769‐5p can directly inhibit the expression of RNF20. Previous studies have shown that HBRE1 /RNF20 is the E3 ubiquitin ligase of hiprotein H2B, and the deletion of RNF20 as a tumour suppressor can lead to the overall decrease of H2Bub level.54, 55