RNA-binding protein that mediates pre-mRNA alternative splicing regulation. Interacts (via C-terminus) with SRSF1. Interacts (via C-terminus) with SRSF2. Colocalizes with splicing factors SRSF1 and SRSF2 in speckles. Expressed in dendritic cells, T-cells, B-cells and natural killer cells. Expressed in secondary lymphoid organs such as spleen and mesenteric, axillary and brachial lymph nodes. Up-regulated in motile T-cells. Belongs to the NSRP1 family.