Fig. 2: DDR1 was highly expressed in CRC and correlated with invasion and migration in vitro.

a mRNA and protein expression levels of DDR1 in colon cancer cell lines compared to normal colon epithelial cells (detected by real-time PCR, fold change shown relative to GAPDH. Three independent experiments are shown). b Protein expression level of DDR1 in colorectal carcinoma tissue compared to normal adjacent tissue. c The gene expression profile of DDR1 across all tumor samples and paired normal tissues (bar plot, the highest bar represents the median expression of certain tumor types or normal tissues. The Y-axis represents transcripts per million (TPM) according to the Gene Expression Profiling Interactive Analysis (GEPIA) database (http://gepia.cancer-pku.cn/). d Western blotting confirmed the construction of MSS and MSI CRC cell lines of both human and mouse origin with stable and transient knockdown of DDR1 induced by shRNA and siRNA transfection. Human MSS cell lines: HT29, SW620; human MSI cell lines: HCT116 and DLD1. Mouse MSS cell line: CT26; mouse MSI cell line: MC38. To achieve a better nockdown effect, we chose si 1 and si 2 for CT26 and MC38, si 1, si 2 and si 3 for HCT116 and SW620, sh1 and sh3 for CT26 and MC38, sh1 and sh2 for SW620 and DLD1 and sh1 and sh4 for HCT116 and HT29 for the following experiments. e Cell proliferation was assessed by CCK-8 assay in both human and mouse CRC cell lines with DDR1 knockdown vs. control siRNA (siNC) transfection. f Apoptosis was assessed based on the percentage of apoptotic cells detected by Annexin V/PI double staining by flow cytometry among the human and mouse CRC cell lines (cells with transient knockdown of DDR1 compared to control cells). g Invasion and migration capacity was assessed by Transwell assay in CRC cell lines with transient knockdown of DDR1 or control transfection. Scale bar, 100 μm. (p < 0.05;** p < 0.01;***, p < 0.001, n.s., not significant).