The Cover

Distribution of naturally occurring missense mutations in the MADH4/SMAD4 MH1 functional domain. Shown are the crystal structures of two molecules of the highly related Smad3 MH1 protein domain bound to DNA. Smad3 MH1 protein is shown in blue and purple, and DNA in green and brown. Homologous amino acid residues targeted by missense mutations in MadH4 are indicated by yellow. For details, see C. A. Iacobuzio-Donahue et al., in this issue.