DNA-binding protein involved in cell cycle control. May act as a transcription activator. Plays role in pre-mRNA splicing as core component of precatalytic, catalytic and postcatalytic spliceosomal complexes. May also play a role in the response to DNA damage (DDR). Component of the precatalytic, catalytic and postcatalytic spliceosome complexes. May shuttle between cytoplasm and nucleus. Belongs to the CEF1 family.