MMP9 and breast cancer: Moreover, macrophage VEGFR1 expression, while dispensable for MAM recruitment, is determinant for the regulation of a set of prometastatic genes in MAMs, such as Csf1 in breast cancer lung metastases (Qian et al., 2015) or Mmp9 in B16 or LLC lung metastases (Hiratsuka et al., 2002, Kaplan et al., 2005).