Other researchers also found that elevated levels of Pi within the tumor microenvironment stimulated expression of the pro-angiogenic gene Forkhead box protein C2 (FOXC2) in breast cancer and lung cancer cells, which regulates neovascularization, a new source of blood vessels to the tumor, and angiogenesis, new growth within blood vessels [133]. This evidence concerns the gene FOXC2 and breast carcinoma.