BCL2 and neoplasm: Subsequent iterative chemical manipulations to improve affinity and decrease binding to human serum albumin, guided by NMR and three-dimensional structures of antiapoptotic proteins, yielded the small molecules ABT-737 and ABT-263, which bind to the hydrophobic pocket of Bcl2 or Bcl-XL with high-affinity and subsequently disrupt the antiapoptotic function of Bcl2 and Bcl-XL with potent anti-tumor effect [2].