Background: SFRS2IP was identified as factor that interacts with SC35, an SR family member critical to mRNA splicing. SFRS2IP contains an arginine-serine-rich (RS) domain and lacks any known RNA-binding motifs. SFRS2IP may have an important role in splicesome assembly since it has been demonstrated to interact with several proteins involved in the early steps of splicesome assembly and the finding that splicesomal complexes A and B are not formed in SFRS2IP depleted extracts.