VEGF and PDGF-A mRNAs were expressed more frequently in breast tumors than in nontumor breast tissues, whereas no difference was found in expression frequency of either transforming growth factor-alpha or basic fibroblast growth factor mRNA.
Also presented is the authors' own work on oncogene expression in breast neoplasms, which implicates the neu, fms, PDGF-A and Ki-ras oncogenes in the control of mammary epithelial cell proliferation by autocrine and paracrine mechanisms.