This protects infiltrating tumor cells in brain from apoptosis via the reduction of expression of sFasL, a death signal, and maintains tumor cell-vascular interaction, mediated by L1CAM, which provides cell adhesion and axonal guidance functions for tumor cells to coopt vascular endothelial network in the brain [31]; and 6) increased basal cell phenotype in brain metastatic lung and breast cancer cells through increased expression of Claudin [48] or FOXC1 [49]. Here, FASLG is linked to breast cancer.