DJ001 (2161306-12-8) is a potent and specific inhibitor of receptor type protein tyrosine phosphatase-sigma (PTPσ) IC50=1.54 μM and >10 μM for 20 other phosphatases.1? Promotes hematopoietic stem cell regeneration in vivo. In mice treated with 5-fluorouracil or irradiated, DJ001 promoted HSC regeneration accelerated hematologic recovery and improved survival. The mode of inhibition of PTPs is via non-competitive allosteric binding. Suppression of radiation-induced HSC apoptosis occurs via activation of Rho GTPase, Rac1 and induction of BCL-XL. Treatment of irradiated human HSCs with DJ001 promotes the regeneration of human HSCs capable of multilineage in vivo repopulation.1