Expression of SRp46 in various cell lines. Aliquots of nuclear extracts, prepared from various human (HeLa, 293, KATO III), simian (CV, COS), and mouse (3T3) cell lines and containing comparable amounts of SR factors as detected with MAb 104 were analyzed by SDS–10% PAGE. SRp46 protein was detected by immunoblot analysis with the P214 antibody. Comparable SRp46 expression levels were observed with the P213 and SC35 antibodies.