PABPC1 and colorectal carcinoma: Based on differential expression patterns in different CRC cells, we knocked down endogenous circPABPC1 in SW620 and LoVo cells using two siRNAs targeting the back-spliced sequence of circPABPC1, and these siRNAs had no effect on both PABPC1 linear mRNA and protein (Fig. 2A, B).