CCDC55, also known as Nuclear speckle-related protein 70 (NSrp70), was initially identified by the NIH Mammalian Gene Collection. Nuclear speckles are known to be the storage sites of mRNA splicing regulators. CCDC55 has been suggested to modulate alternative pre-mRNA splicing in vivo. It co-localizes and physically interacts with the SR proteins SC35 and ASF/SF2, essential splicing factors which are required for constitutive splicing and can regulate alternative mRNA splicing. Loss of CCDC55 in mice leads to early embryonic lethality highlights the importance of the functional role of CCDC55.Synonyms: Coiled-coil domain-containing protein 55, HSPC095, NSrp70