Given that vasculogenesis is vital for tumor growth and progression (Weis and Cheresh, 2011) and MMP2 and MMP9 have been implicated in angiogenesis (Schnaper et al., 1993; Seftor et al., 2001; Itoh et al., 1998; Vu et al., 1998), we next tested whether Rab40b knockdown is required for primary tumor vascularization. This evidence concerns the gene MMP9 and neoplasm.