Effect of mutations of

cis regulatory elements in the murine STAT3 gene on in vivo splicing of minigene constructs. (A) RT-PCR analysis using primers specific for the β splice product (pspl-b-F1 and pspl-E24-R) of RNA isolated from the indicated cells transfected with WT construct or construct containing the indicated point mutation (A to G, C, or T) in the β 3′ AS. (B) RT-PCR analysis using vector-derived primers duSD2 and duSA4 of RNA isolated from HeLa cells transfected with WT construct or constructs containing the indicated point mutation (A to G, C, or T) in the α 3′ AS. (C) RT-PCR analysis using vector-derived primers duSD2 and duSA4 of RNA isolated from untransfected HeLa cells or HeLa cells transfected with WT construct or construct in which the δ 3′ AS AG was replaced by TC and the α AS CAG was either deleted (Δ) or the A was mutated to G, C, or T. (D) RT-PCR analysis using vector-derived primers SD6 and SA2 of RNA isolated from untransfected HeLa cells or HeLa cells transfected with WT construct or construct containing the ΔA, ΔB, ΔC, or ΔD deletions. The 100-bp DNA ladder is indicated by M; the position of the 600-bp band is shown. The sequence-confirmed products of the RT-PCR are shown schematically to the right of each gel.