Effects of FHL1 overexpression or knockdown on aggressive proliferation of colorectal cancer cells were studied. A,B. FHL1 mRNA and protein levels were measured in 5 CRC cell lines and normal colon epithelial cells by qRT-PCR (A) and Western blot (B). C, E. FHL1 gene expression and protein levels were evaluated in HT-29 cells after transfection with the overexpression plasmid. D, F. The silencing effect on FHL1 by three siRNAs was evaluated in HCT-116 cells using qRT-PCR (D) and Western blot (F). G. The colony formation potential of HCT-116 and HT-29 cells after FHL1 knockdown by siRNA-3 or FHL1 overexpression by Lv-GFP+FHL1 was analyzed with a colony formation assay. H-I. The proliferation of HCT-116 and HT-29 cells after FHL1 knockdown by siRNA-3 or FHL1 overexpression via Lv-GFP+FHL1 was measured using a CCK-8 cell-counting kit. Data are presented as mean ± SD and are representative of 3 independent experiments. * P < 0.05, ** P < 0.01, *** P < 0.001.