Quantitative analysis of SPAM1 expression in normal human tissues. Primers were used in real-time RT-PCR assays to amplify transcripts specific for GAPDH and total SPAM1 transcripts, and, in testis only, for SPAM1 transcripts initiating in exon 1A and 1B. Green bars represent the relative abundance of total SPAM1 transcripts normalized to GAPDH. Solid and hatched blue bars represent the contribution of exon 1A and 1B transcripts, respectively, to total SPAM1 expression. All bars represent the mean of four independent assays ± standard deviation.