KL and colorectal carcinoma: Klotho expression may have either positive or negative effects on colonic tumourigenesis (Fig. 2A); however, since klotho deficiency is linked to enhanced ageing [17,18,20,19,21] and to chronic kidney disease (CKD) [44], and since klotho expression is down-regulated in CRC [23,24], therapeutic approaches to up-regulate klotho expression are more likely to be adopted.