Comparison of PCR vs. hybridization pattern on the arrays. A. Electrophoresis of PCR products. Initially reverse transcribed c-DNA of human fibroblasts, DLD-1 and 97TM1 was used as template for PCR with specific primers for Matriptase, PAI-1 and PAI-2. Positive controls: plasmid-cDNAs of the three targets, negative controls were template free. Product sizes: matriptase 470 bp, PAI-1 687 bp, PAI-2 710 bp. B. Array analysis. Sample preparation was performed according to the protocol for overall linear amplification with the SPA primer and simultaneous labelling (see Methods part).