Binds to WASL/N-WASP and suppresses its translocation from the nucleus to the cytoplasm, thereby inhibiting its cytoplasmic function (By similarity). Plays a role in the regulation of cell morphology and cytoskeletal organization. Required in the control of cell shape and migration. May play a role in cytokinesis. May be involved in pre-mRNA splicing. Interacts with the N-terminus of HTT. Interacts with the phosphorylated C-terminal domain of POLR2A. Interacts with AKAP8L, SF1, SRPK1, ENAH, ATBF1 and MECP2 (By similarity). Interacts through the WW domains with formin proline-rich regions and with WASL/N-WASP (By similarity). Colocalizes with AKAP8L in the nuclear matrix. Expressed in the brain cortex (at protein level). Widely expressed. The WW domains are essential for localization to nuclear speckles. Probable target of nonsense-mediated mRNA decay. Belongs to the PRPF40 family. Extended N-terminus. Truncated N-terminus. Extended N-terminus. Contaminating sequence. Potential poly-A sequence starting in position 409. Truncated N-terminus.