PDK4 and malignant colon neoplasm: Recently, PDHK4 has been shown to promote tumorigenesis through mTORC1 signalling41 and knockdown of PDHK4 has been shown inhibit colorectal tumour growth.42 In addition, PDHK4 expression is positively correlated with drug resistance in colon cancer cells and induced by 5-FU.42, 43 In contrast, other studies have proposed a specific suppressive role on proliferation after PDHK4 upregulation in MCF-10A mammary epithelial cells and lung tumour cells following PPARγ upregulation.44, 45 Further work report that PDHK4 expression could be regulated by different microRNAs.