For example, COX-2 and VEGF-C mRNA expression could also be observed in normal breast epithelium [27,28], RT-PCR assay could not to reveal the two molecules expression exactly if microdissection was not performed, as well as the possibility that stromal cells and/or immigrant leukocytes may also be the source of both molecules except for the breast cancer cells. This evidence concerns the gene PTGS2 and breast cancer.