Differential expression of secreted semaphorins and VEGF 165. RT-PCRs were performed using total RNA from human CD34⁺/CD38⁻ cells and from murine MS-5 cells (see Materials and Methods). Expected PCR products are 130 bp for human semaphorin IV, 430 bp for human semaphorin III, 410 bp for human semaphorin V, 255 bp for human and murine semaphorin E, 260 bp for VEGF 165, 260 bp for murine semaphorin IV, 720 bp for murine semaphorin V, and 530 bp for murine semaphorin III. Controls consist of amplification with either S14 primers (human samples) or HPRT primers (murine samples).