BOP (N-(Benzenesulfonyl)-L-prolyl-L-O-(1-pyrrolidinylcarbonyl)tyrosine sodium salt) is a potent and selective dual inhibitor of integrins alpha-4 beta-1 (A4β1) and alpha-9 beta-1 (A9β1) with Kd values in the picomolar range. BOP has been shown to preferentially mobilize hematopoietic stem cells (HSCs) and progenitors and to act synergistically with AMD3100.
