Fig. 1

Experimental outline. a Mammalian Expi293F cells were transfected with a pCDNA3.4-KLK9 plasmid and used to produce mat-KLK9. Recombinant mat-KLK9 was purified with a 2-step chromatographic separation (anion-exchange followed by reverse-phase chromatography). KLK9 purity was assessed by silver staining (left panel) and western blot; the major KLK9 band is around 42 kDa. b Mice were immunized for production of anti-KLK9 monoclonal antibodies. c An immunocapture-PRM assay was utilized for the optimal selection of high affinity anti-KLK9 mAbs. d Purified monoclonal antibodies were used in pairs for the development of a sandwich type ELISA. PRM, Parallel reaction monitoring