Single-stranded cDNA was generated from 5 fig total RNA using the AMV reverse transcriptase system (Gibco BRL Life Technologies Inc., Paisley, U.K.) and the primer 5'-GACTCGAGTCGACATC-
cDNA was then ethanol precipitated and resuspended in PCR reaction mix containing either of the feline CD9 gene-specific primers F9-l+, 5'-CGCAGGAGTT-TATATTCTGATTGGAGCTGGTCC-3' and F9-2+, 5-TGTATCAAATACCTGCTCTTCGGATTTAAT-3', the human CD9 gene-specific primers H9-l+, 5'-CATGCCGGTCAAAGGAGGCACCAAGT-3' and H9-2+, 5-CAGACCAAGAGCATCTTCGAGCAA-GAA-3', and the adapter primer 5'-GACTC-GAGTCGACATCGA-3' (25 pmol of each)