SLITRK4 and hepatocellular carcinoma: To study the mechanism of how miR-139-5p decreases the HCC cells invasion and proliferation capacities, we first searched the OncomiR database to predict some potential downstream genes, and from the eight potential targets, we selected three genes for further study (PCDH7, SLITRK4 and UGT2A3, miRDB Score>70) (Figure 3A).