4ISK:
reference: Development and Binding Mode Assessment of N-[4-[2-Propyn-1-yl[(6S)-4,6,7,8-tetrahydro-2-(hydroxymethyl)-4-oxo-3H-cyclopenta [g]quinazolin-6-yl]amino]benzoyl]-l-gamma-glutamyl-d-glutamic Acid (BGC 945), a Novel Thymidylate Synthase Inhibitor That Targets Tumor Cells., Tochowicz A, Dalziel S, Eidam O, O'Connell JD 3rd, Griner S, Finer-Moore JS, Stroud RM, J Med Chem. 2013 Jun 21. PMID: 23710599

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).