RBM interacts with SR proteins in NEs. (A) Samples of thioredoxin and mRBMIR were attached to agarose beads. To show equal loading protein was eluted, separated by SDS-PAGE, and stained with Coomassie blue. (B) SR proteins pulled down from NEs by the respective beads were analyzed by SDS-PAGE followed by Western blotting, and probing with mAb 10H3 (lanes 1–5); or for single SR species ASF/SF2 (lanes 6–10), 9G8 (lanes 11–15), or SC35 (lanes 16–20). Note that the presence of high amounts of mRBMIR in lanes 3, 8, 13, and 18 alter the mobilities of the SRp40 and SRp30 protein. (C) Pull-down of ASF/SF2 is RNA independent, while U1-70K or TATA-binding protein are pulled down very weakly by linking RNAs.