Our studies of lung cancer have suggested a potential cross-talk between cancer cells and the microenvironment, controlled by CSF1/Vav1 signaling pathways (Sebban et al, 2014), whereby Vav1 positively regulates the expression of CSF1, a growth factor that can lead to Vav1 activation in the microenvironment of tumor cells and in the immune cells in the microenvironment. Here, CSF1 is linked to lung cancer.