KDR and hepatocellular carcinoma: Together with the association found between high levels of NRP1 and invasion and metastasis, two of the included studies reported that NRP1 expression is positively correlated with VEGFR2 in HCC [27], and that not only NRP1, but also VEGF and VEGFR1/3 overexpression, were associated with poor prognosis in CRC patients [22].