TK1 and hepatocellular carcinoma: With correlation of expression profiling of metabolic RLEs and differentiation status of TCGA-LIHC and HCC cell lines, we revealed that upregulated RLEs in pyrimidine metabolism especially the 3 RLEs (TK1, TYMS and DTYMK) of dTTP biosynthesis pathway play critical roles in increasing cellular dTTP concentration and sustaining the stemness properties.