In one of our studies, 1D SDS-PAGE gel electrophoresis in combination with column chromatography, zymography, and tandem MS (MS/MS) facilitated the identification of MMP-2 (P < 0.001) and MMP-9/NGAL (P = 0.003) by multivariable regression as independently predictive in differentiating prostate cancer patients and controls. This evidence concerns the gene MMP9 and prostate cancer.