. "Edited: Jassal, B, 2006-01-18 10:19:52"^^ . "Reviewed: Heldin, CH, 2006-04-18 14:26:12"^^ . "Activated type I receptor kinase directly phosphorylates two of the C-terminal serine residues of SMAD2 or SMAD3. Binding of these R-SMADs to the L45 loop of the type I receptor is critical for this event."^^ . "Reviewed: Huang, Tao, 2012-05-14"^^ . "Authored: Heldin, CH, Moustakas, A, Huminiecki, L, Jassal, B, 2006-02-02"^^ . . . . . . "Activated type I receptor phosphorylates SMAD2/3 directly"^^ . . . . . . .