Figure 3.

Semiquantitative RT-PCR of VEGF mRNA expression. Equal amounts of cDNA from cells before isolation (Mk. before), CD41a⁺ (Mk. pos.), and CD41a⁻ (Mk. neg.) cells were amplified by RT-PCR for VEGF and β-actin expression using different numbers of amplification cycles. VEGF₁₂₁ and VEGF₁₈₉ were detected after 25 PCR cycles only in CD41a⁺ cells. Furthermore, VEGF₁₆₅ was detected after 30 cycles only in these cells. In contrast, no difference in the β-actin expression was observed. After 35 PCR cycles, PCR products corresponding to the three VEGF isoforms could also be amplified from CD41a⁻ and unseparated cells. As a negative control, RNA without RT was also subjected to 35 cycles of PCR amplification (VEGF/no RT).