Our own group has shown that HER2-positive CAFs secrete soluble factors, such as FGF5, that are able to switch the phenotype of HER2-positive breast cancer cells from sensitive to resistant to trastuzumab and lapatinib [66], in agreement with other results, obtained in 3D co-cultures of fibroblasts and breast cancer cells in which the later were protected from lapatinib [67]. This evidence concerns the gene ERBB2 and breast cancer.