SLITRK4 and hepatocellular carcinoma: To assess the function of SLITRK4 under the regulation of miR-139-5p in HCC, we added miR-139-5p inhibitor and knocked down SLITRK4 in HCC cells, and the reverse assays showed that knocking down SLITRK4 could partly reverse miR-139-5p inhibitor’s function to HCC invasion and proliferation, both in HCC SK-HEP-1 and HA22T cells (Figure 4A–D).