(A) ROC curves (percent of known ligands found vs. percent of ranked database). The results from the ideal, default, and modified protocols and random picking are presented in solid black, green, red and dashed black curves, respectively. (B) Curve of φ values vs. percent of ranked database. A red point indicates the coordinate of the suggested reference compound, ZINC03814717. (C) Compound ZINC03814717 (the 2D structure is shown as an inset) in the binding pocket of COX-2 together with the crystal structure of compound 1 (the 2D structure is shown as an inset) [11]. Only residues forming hydrogen bonds are shown here. The residues are presented as lines, and the ligands are presented as sticks. Carbon atoms are presented in green for COX- 2, magenta for compound 1 and cyan for compound ZINC03814717. Polar hydrogen atoms are presented in white, fluorine atoms are presented in light blue, nitrogen atoms are presented in blue, oxygen atoms are presented in red, and sulfur atoms are presented in yellow. Dashed black lines indicate the hydrogen bonds. The 3D figure was created using PyMOL 1.2 (http://www.pymol.org/).