NCK-interacting protein with SH3 domain is a protein that in humans is encoded by the NCKIPSD gene.

The protein encoded by this gene is localized exclusively in the cell nucleus. It plays a role in signal transduction, and may function in the maintenance of sarcomeres and in the assembly of myofibrils into sarcomeres. It also plays an important role in stress fiber formation. The gene is involved in therapy-related leukemia by a chromosomal translocation t(3;11)(p21;q23) that involves this gene and the myeloid/lymphoid leukemia gene. Alternative splicing occurs in this locus and two transcript variants encoding distinct isoforms have been identified. [provided by RefSeq, Jul 2008].
Function: Has an important role in stress fiber formation induced by active diaphanous protein homolog 1 (DRF1). Induces microspike formation, in vivo (By similarity). In vitro, stimulates N-WASP-induced ARP2/3 complex activation in the absence of CDC42 (By similarity). May play an important role in the maintenance of sarcomeres and/or in the assembly of myofibrils into sarcomeres. Implicated in regulation of actin polymerization and cell adhesion.