Citrate, an intermediate of tricarboxylic acid cycle, plays a crucial role for the generation of biochemical energy and synthesis of fatty acids and cholesterol in liver. The cellular uptake of citrate is mediated by Na⁺-coupled di- and tricarboxylate transporters, particularly NaCT. Since NaCT expression level in liver is closely related to the pathogenesis of metabolic diseases, such as non-alcoholic fatty liver disease. Therefore, it is important to elucidate the regulation mechanism of NaCT function in liver. In this study, we focused on protein kinase C (PKC), and evaluated the influence of PKC activation on the citrate transport in human hepatocellular carcinoma HepG2 cells. The uptake of citrate in HepG2 cells depended on Na⁺, and it also occurred via a saturable process. Its Michaelis constant (K_m) and maximal velocity (V_max) was 5.12 mM and 106 nmol/mg protein/30 min, respectively. These results suggest that the citrate transport in HepG2 cells is primarily mediated by NaCT. In addition, we observed that the Na⁺-dependent citrate uptake in HepG2 cells was significantly decreased by the preincubation of the cells with phorbol 12-myristate 13-acetate (PMA), a PKC activator. We also found that this decrease of citrate uptake by PMA was attributed to the reduction of V_max, without affecting K_m value. These results indicate that PKC regulates the transport activity of NaCT in HepG2 cells. The present findings contribute to the elucidation of the regulation mechanism of NaCT function in hepatic metabolic diseases.