DG ligation regulates sustained activation of STAT5. (A and B) Expression of wild-type (wt) or cytoplasmic domain–deleted DG (DG Δ cyto) in DG−/− cells restored the sustained STAT5 activation (A) and β-casein transcription (B). (C) A scheme showing that the integrated signals from laminin-111 and Prl regulate mammary-specific function. Gray portion shows the differences in molecular mechanisms between our current results and previous studies (Tourkine et al., 1995).