FIG. 4.

hnRNP H and hnRNP F antagonize 9G8-mediated activation. (A) In vitro splicing reactions were performed with the enhancer-containing dsx-TM in the presence of 1.5 μM 9G8 and increasing amounts of hnRNPs H and F (750 nM, 1.5 μM, and 3 μM). Similar amounts of PTB and SRp20 were added as controls. (B) The wild-type α-TM construct (pSVpA α-TM 1-4; 400 ng) was cotransfected into PAC1 cells with increasing amounts of hnRNP H or hnRNP F (100 ng, 800 ng, and 3.2 μg), and splicing patterns were analyzed as in Fig. 1. At the highest transfection levels, hnRNP H and hnRNP F fractions were increased 3.1- and 3.4-fold, respectively (see Fig. S2 in the supplemental material). (C) Western blots of whole-cell lysates from PAC1 and HeLa cells were performed with antibodies to hnRNP H, hnRNP F, 9G8, and α-tubulin.