(A) Upper panel shows a comparison between the AS1 + AS2 sequence and the heterologous polypurinic sequences from the EDA ESE and the Apo AII ISE elements. The column on the right shows the SR protein-binding specificity of all these sequences as previously determined by immunoprecipitation analysis. The EDA ESE and Apo ISE sequences were then inserted in the pES plasmid (as shown in the lower panel), thus creating constructs pTB EDAPK and pTB ApoISEPK, respectively. The levels of CFTR exon 9 inclusion displayed by these three plasmids in Hep3B cells and compared with that of the pES and pTB AS1 + AS2PK constructs is reported in (B). A quantification of three independent experiments is reported in (C). (D) Shows the response of the TG11T5, pTB AS1 + AS2PK, pTB EDAPK and pES plasmids to SF2/ASF overexpression, and of the response of the pTB AS1 + AS2PK construct to SC35 overexpression, following transfection in Hep3B cells.