In addition, the fact that the OPN inhibitor Agelastatin A blocked SUM1315 lung metastasis but not primary tumorigenesis in mouse xenografts established with isolated post-co-culture cancer cells is consistent with our earlier report that co-implantation of breast cancer cells with Tiam1-deficient fibroblasts affected metastasis but not primary tumorigenesis [28]. This evidence concerns the gene SPP1 and breast cancer.