Signal transducer and activator of transcription 2 (STAT2) is a member of the transcription factor STAT family with an apparent M.W. of 113kD in SDS-PAGE gels. Human STAT2 is 851aa in length and contains one SH2 domain (aa572-667). Splicing variants produce two isoforms for human STAT2. The short isoform has a 32aa substitution and a 199aa deletion corresponding to aa 621-652 and aa653-851 in the long isoform, respectively. Human STAT2 shares 73% and 65% aa sequence identity with rat and mouse STAT2, in that order. STAT2 functions as a signal transducer and activator of transcription that mediates signaling by type I IFNs (IFN-alpha and IFN-beta), and it is also required for myogenic differentiation.