PARK7 and hepatocellular carcinoma: To investigate if DJ-1 is one of the secretory factors in HCC cell culture medium and functions to help endothelial cells for their angiogenesis and migration, DJ-1 level in culture medium was assessed by ELISA, and the results showed that DJ-1 was secreted in HepG2, HUH-7, and L02 cells at an average of 5.68, 8.77, and 2.62 pg/mL in 24 h, respectively, and DJ-1 level increased to an average of 11.55, 16.44, and 4.53 pg/mL at 48 h, respectively (Figure 2(a)).