Furthermore, in situ proximity ligation assay (PLA) indicated that the gain-of-function of COX-2 in HCC cells increased the formation and number of red fluorescence foci, indicative of enhanced COX-2/p-Drp1Ser616 proximity, and thus increased the interaction between these two proteins in the mitochondria (Figure 3E). The gene discussed is PTGS2; the disease is hepatocellular carcinoma.