Figure 2. Relative expression level of the VEGF isoforms in normal tissues and tumors.

This ternary diagram depicts relative isoform expression based on mRNA RT-PCR of cell culture, or of embryonic, adult, and tumor tissues (see Supplemental Table S5). The location of each point on this ternary diagram denotes the relative expression of VEGF₁₂₁, of VEGF₁₆₅, and of the exon 6-containing isoforms grouped together; VEGF₁₄₅ typically has low levels of expression and VEGF₁₈₃ seems to be functionally equivalent to VEGF₁₈₉ (62). At vertices, all VEGF expression is comprised only of that isoform, while the midpoint of the opposite edge would indicate 0% expression of that isoform and 50% expression each of other isoforms. Each point represents specific organs from individual studies; points with the same color denote the same organ of origin; circles: tumors, squares: normal embryonic or adult tissue. The dashed line represents a line of equal VEGF₁₂₁:VEGF₁₈₉ expression, as discussed in Section 5.2; the VEGF₁₆₄-only and VEGF_120/188 mice would be expected to fall on this line. Note that most tumors fall below this line (i.e. high VEGF_120/121 expression).