The protein encoded by this gene is part of a heteromeric complex that binds U4, U5, and U6 small nuclear RNAs and is involved in pre-mRNA splicing. The encoded protein also is a mitotic checkpoint protein and a regulator of chemoresistance in human ovarian cancer. Several transcript variants encoding different isoforms have been found for this gene. The removal of introns from nuclear pre-mRNAs occurs on complexes called spliceosomes, which are made up of 4 small nuclear ribonucleoprotein (snRNP) particles and an undefined number of transiently associated splicing factors. PRPF4 is 1 of several proteins that associate with U4 and U6 snRNPs.