Fig. 3. hSlu7 effect is specific to 3'ss selection. (A) The E1A pre-mRNA containing three alternative 5'ss (9S, 12S and 13S, from distal to proximal). The 10S product is produced by aberrant splicing that does not involve simple competition between alternative 5'ss (Stephens and Harlow, 1987). (B) Spliced products were analysed following RT-PCR using primers on either side of the alternative exon (A, arrows). (bottom) RT-PCR carried out on a control GAPDH gene. (C) The relative amounts of 9S, 12S and 13S used in B expressed out of the total amount of spliced products in the same lane and experiment.