We further investigated the NRP1 expression in SP cells of PLC/PRF/5 and HuH-7 and found that the expression of NRP1 in SP cells was much higher than that in NSP cells of PLC/PRF/5 (9.29% compared with 2.08%) and of HuH-7(1.82% compared with 1.17%; Figure 7A), indicating that NRP1 played a vital role in SP cells of HCC. This evidence concerns the gene NRP1 and hepatocellular carcinoma.