To further investigate the relationship between TGF-β expression and formation of CAFs in tumor microenvironment, we employed starved NIH3T3 fibroblasts in vitro and 4T1 cells mixed with NIH3T3 fibroblasts xenograft tumor model in vivo to simulate nutritional deprivation of tumor microenvironment. The gene discussed is TGFB1; the disease is neoplasm.