HnRNPE3 interacts with hnRNPE2 and SRA4, both also moderate activators of exon 10 splicing, and the three activators act additively. Western blots of (A, B) protein lysates and (C) co-IPs from 1:1 co-tranfections of myc-hnRNPE3 and FLAG-factors in HEK293 cells. Protein markers markers are indicated on the right of each panel. The positions of factors are indicated on the left. (A) Input, factors detected by anti-FLAG monoclonal antibody M2. (B) Input and (C) co-IP, hnRNPE3 detected by anti-myc polyclonal antibody. (D) RT-PCR of SP/10L in COS cells co-transfected with various combinations of FLAG constructs of hnRNPE3, SRA4 and hnRNPE2. Primers and graph conventions are as in Fig.1C.