PTK2 and renal cell carcinoma: The down‐regulation of miR‐28‐5p has been reported in multiple cancers, such as renal cell carcinoma,48 CRC49, 50 and HCC.51 Increasing evidence indicates that miR‐28‐5p negatively regulates a number of well‐characterized oncogenic proteins, such as CCND1, HOXB3,29 IL‐34, FAK, ERK1/251 and insulin‐like growth factor 1.52 In this study, miR‐28‐5p expression was down‐regulated in CRC samples compared with that in normal colon samples, and the down‐regulation of miR‐28‐5p forecasted a poor prognosis for CRC patients, suggesting that this miRNA plays a tumour‐suppressive role.