HSPG2 and hepatocellular carcinoma: Among the signaling pathways examined, we found that only the phosphorylation level at AKT phosphorylation sites Ser473 and Thr308 were significantly increased in CCDC137-overexpressing Huh7 and HCCLM3 cells and correspondingly decreased when CCDC137 was knocked down in PLC/PRF/5 and JHH-7 cells (Fig. 4a, b; Supplementary Figure S3a, b), suggesting that CCDC137 positively regulates the AKT signaling pathway in HCC cells in vitro.