PCSK9 and colonic neoplasm: In this regard, our data showed that PCSK9 regulated MIF expression and lactate and protein lactylation levels in colon cancer cells (Fig. 6); thus, we co-cultured HCT116 or HT-29 cells after PCSK9 knockdown (Fig. 7a) with THP-1-derived macrophages using the Transwell system and detected the expression of the M1/M2 markers using qRT-PCR, Western blot, and Flow cytometry assay.