Oligonucleotide primers were synthesized corresponding to nucleotides 51 to 76 (sense) and 256 to 290 (antisense) of human CD9 (Boucheix et al., 1991; Lanza et al., 1991) and 1/zg of each was added to PCR mix comprising 200 /zM dNTPs, 1.5 mM MgCl2, 50 mM KC1, 10 mM Tris-HCl pH 8.3 and 100 ng of single-stranded cDNA template