Identification and characterization of the human <i>PIK3CA</i> promoters.

<p>A. Illustration of the structure of human <i>PIK3CA</i> gene and its 5′ upstream regulatory region. B. A region highly rich in GC is found in the <i>PIK3CA</i> 5′TRR. C. Illustration of the primers used for mapping RT-PCR of the <i>PIK3CA</i> transcriptional start site (SST). D. Results of mapping RT-PCR. There is no band between the forward primer F1 located upstream of the SST and the reverse primer R located on exon 1 of <i>PIK3CA</i>. The right size bands could be detected between primer F2 or F3 (both located downstream of SST) and reverse primer R. E. A small splicing variant is found in the 5′UTR of human <i>PIK3CA</i> gene, which can also be detected by mapping RT-PCR (primers F2 and R). F. Summarized results of the transcriptional activity of <i>PIK3CA</i> TRR fragments.