Sister chromatid cohesion, which depends on cohesin, is essential for the 
faithful segregation of replicated chromosomes. Here, we report that splicing 
complex Prp19 is essential for cohesion in both G2 and mitosis, and consequently 
for the proper progression of the cell through mitosis. Inactivation of splicing 
factors SF3a120 and U2AF65 induces similar cohesion defects to Prp19 complex 
inactivation. Our data indicate that these splicing factors are all required for 
the accumulation of cohesion factor Sororin, by facilitating the proper splicing 
of its pre-mRNA. Finally, we show that ectopic expression of Sororin corrects 
defective cohesion caused by Prp19 complex inactivation. We propose that the 
Prp19 complex and the splicing machinery contribute to the establishment of 
cohesion by promoting Sororin accumulation during S phase, and are, therefore, 
essential to the maintenance of genome stability.