An inhibitor of protein tyrosine phosphatases; increases phosphorylated substrates of the phosphatase SHP-1 in Jurkat T cells; selective for SHP-1 over SHP-2, having low activity at the SHP-2 substrate pERK1/2; increases pLck-pY394 levels by ~3.3-fold and increases the number of IFN-γ+ spleen cells in mouse spleen ex vivo (~3 mg/kg); inhibits tumor growth in a B16 melanoma mouse xenograft model (3 mg/kg per day, oral)