We decided to determine the effect of PEMn and its IC50 during the proliferation of several cell lines characterised by the overexpression of VEGF receptors as Flt-1 (VEGFR-1) in osteosarcoma MNNG-HOS [25] and melanoma A-375 cell lines [25], and Flk-1 (VEGFR-2) in breast cancer MDA-MB-231 [25] and prostate cancer PC-3 cell lines [25]. The gene discussed is KDR; the disease is breast cancer.