RT-PCR analysis of VEGF-A mRNA splice variants synthesized by HIV-1–infected HUT 78 cells. RT-PCR was performed with specific primers, which allow discrimination of the different splice variants of VEGF-A mRNA by the length of the polymerization products. As a control, PCR products obtained with cDNA of a human epithelial cell line (A 431) known to produce VEGF-A are shown (A). The two splice variants coding for the secreted forms of VEGF-A, VEGF₁₂₁and VEGF₁₆₅ (131- and 263-bp amplification products) and the cell-associated VEGF₁₈₉ (335 bp) were found to be synthesized in HUT 78 cells infected with HIV-1 (B). The PCR product corresponding to the mRNA splice variant encoding VEGF₁₆₅was the most prominent, the one corresponding to VEGF₁₂₁could be detected to a lesser extent, and the one corresponding to VEGF₁₈₉ was only present in minimal amounts.