We recently discovered the physical engagement between STAT3 and NPM1 in cancer cells.17 Moreover, it was documented that STAT5 physically associates with centrosomal P4.1-associated protein22 and that NPM1 regulates centrosome duplication.23 These findings prompted us to ask whether a physical interaction exists between STAT5 and NPM1. The gene discussed is STAT5A; the disease is cancer.