Schematic representation of protein interactions in the FA pathway. DNA lesions arising during normal S-phase or after DNA damage activate ATR-dependent phosphorylation and FA core complex–dependent monoubiquitination of both FANCD2 and FANCI. The ID complex consisting of monoubiquitinated FANCD2 and FANCI forms nuclear foci in chromatin. USP1 deubiquitinates both proteins.

Reprinted from Developmental Cell, vol. 23. Grompe M, van de Vrogt H. The Fanconi family adds a fraternal twin; pp 661–662, 2007, with permission from Elsevier.³⁷