PPIA and colorectal carcinoma: Real-time PCR analysis showed that upregulation of TFAP2C increased, while silencing TFAP2C decreased expression levels of multiple downstream genes, including CTGF, CYR61, HOXA1 and SOX9 in CRC cells, but had no effect on expression levels of house-keeping genes RPL13A and PPIA (Fig. 6g).