TKTL1 and neoplasm: In addition to CYP24A1, five other genes were commonly up-regulated in tumor slices exposed to both low and high concentrations of 1,25(OH)2D3: DPP4, KCKN3, EFTUD1, TKTL1 and CA2. All, except TKTL1 (transketolase-like 1) have been previously identified as VDR target genes in various model systems.