CD45 Phosphatase Inhibits STAT3 Transcription FactorActivityinMyeloidCellsandPromotesTumor

Gabrilovich and colleagues demonstratethat tumor monocytic cells rapidlydifferentiate to macrophages due tohypoxia inducible decrease of STAT3activity. Inhibition of CD45 phosphatasemediated by sialic acid was responsiblefor this effect. Degradation of sialic acidsensitized tumor myeloid cells to STAT3inhibitor, resulting in potent antitumoreffect.