LYP-IN-1 is a potent, selective and specific LYP inhibitor with a Ki and an IC50 of 110 nM and 0.259 μM, respectively. LYP-IN-1 also has selectivity for a large panel of PTPs, such as SHP1 (IC50=5 μM) and SHP2 (IC50=2.5 μM). LYP-IN-1 exhibits highly efficacious cellular activity in T- and mast cells. LYP-IN-1 can be used for the study of autoimmune disorders.