Figure 4.

Three exemplary promiscuity cliffs (PCs) formed by multiclass ligands (left) and non-promiscuous or consistently inactive screening compounds (right) are shown. Structural modifications are highlighted. Below each compound, the number of targets it was tested (top) and active against (bottom) is given. Red numbers above arrows report shared tested targets. For example, the PC at the bottom of the figure consisted of a multiclass ligand that was tested against 178 targets and active against 34 of them and a compound that was consistently inactive against all 195 targets it was tested against. These two compounds, which were only distinguished by a chlorine substitution, were tested against 170 shared targets.