PON2 and renal cell carcinoma: Furthermore, significant reductions in PON2 expression at both the mRNA and protein levels were observed in human renal cell carcinoma lines treated with chemotherapeutic agents such as cisplatin (CDDP) and 5-fluorouracil (5-FU), as well as through shRNA-mediated gene silencing, which also contributed to a decrease in cell proliferation rates.