Proteins within a 10 nm radial proximity of ligase-fused menin were biotinylated in breast cancer cells transduced with doxycycline-inducible BirA-menin in the presence of biotin and doxycycline, and the labeled proteins were pulled down by streptavidin-beads (Figure 2A,B) [19,21]. The gene discussed is MEN1; the disease is breast cancer.