MMP11 and breast cancer: MMP-11 and PDGF-C protein levels were remarkably higher in sera of breast cancer patients than in sera of healthy volunteers (MMP-11: 53.07 ± 2.63 ng/mL versus 8.16 ± 0.14 ng/mL, PDGF-C: 1023.00 ± 47.76 pg/mL versus 524.90 ± 15.01 pg/mL).