Part of the signal that specifies dorsal cell fates in the embryo. Acts together with dpp. Heterodimers of scw/dpp are the active subunit, dpp/dpp homodimers elicit a basal response and scw/scw homodimers alone are ineffective in specifying a dorsal pattern. Ubiquitously expressed during early stages of embryogenesis, but the effect on development appears graded and is restricted to the dorsal side of the embryo. Expressed both maternally and zygotically. Highest embryonic expression is found during syncytial blastoderm (nuclear cycles 11-12). Expression declines rapidly at cellular blastoderm stage 5 and is not detected during the rest of embryonic development. Belongs to the TGF-beta family.