UNC3474 is a small molecule ligand, binding with 53BP1. UNC3474 binds the aromatic methyl-lysine binding cage of 53BP1TT, with a dissociation constant (Kd) of 1.0 ± 0.3 μM. UNC3474 inhibits the recruitment of 53BP1 to DSBs by stabilizing a pre-existing autoinhibited state of 53BP1 in cells[1].