ARHGEF5 and neoplasm: The ARHGEF5 gene was originally identified as an oncogene by focus formation assays in NIH3T3 cells.28, 29 Recent reports showed that ARHGEF5 upregulation promotes tumorigenesis,30 and that coexpression of ARHGEF5 and Src is associated with poor prognosis of patients with non-small-cell lung cancer.31 In addition, ARHGEF5 overexpression markedly increase Src-induced tumor growth,21 implying that the Src-ARHGEF5 pathway has important roles not only in invasion and metastasis but also in tumor growth.