WRN and BLM functional protein interactions. (a) Protein interacting partners of WRN are indicated according to functional effect. Note that this list only includes functional protein interactions (i.e. interactions that modulate the function of one or both of the protein partners (see elsewhere for further discussion). The target WRN activity is shown in parentheses. (i) Proteins that stimulate WRN. (ii) Proteins that are stimulated by WRN. (iii) Proteins that inhibit WRN. (iv) Proteins that are inhibited by WRN. Proteins that have analogous interactions with both WRN and BLM are shown in red. (b) Same as part (a), except for BLM. Abbreviations: exo, exonuclease; FLAP, DNA flap; hel, helicase; TOP1, topoisomerase I.