Figure 2. Differential MDM2 exon usage. (A) Genomic structure of the human MDM2 promoter region. The locus has two independent promoters before exons 1a (P1) and 1b (P2), yielding long- and short-5’ UTR isoforms, respectively. Translation start site (ATG) in exon 2 is indicated. Red triangles indicate p53 protein binding sites involved in P2 activation. (B) In H2O2 treated HUVEC, short-5’ UTR isoforms of MDM2 were induced, as assessed by qPCR using primers spanning from exon 1b to exon 2. Modulation of long-5’ UTR isoforms of MDM2 was not statistically significant, as assessed by qPCR using primers spanning from exon 1a to exon 2. The bar graph represents average values ±SEM (n= 3; *p<0.05, ***p<0.001).