MMP11 detection in plasma samples. A) standard curve of the ELISA assay. MMP11 recombinant protein was diluted in 1:10 dilution of a normal control plasma. B) MMP11 was measured by ELISA in breast (BR) and prostate (PROST) cancer plasma samples as described in Methods. Control (C) samples were obtained from healthy donors. The assay was run in duplicate and repeated twice, with a inter-variability of 7.6%. A threshold at 100 ng/ml was determined (see text) to identify positive and negative plasma samples.