– LMTK3-IN-1 (compound C28) is an ATP-competitive inhibitor of lemur tyrosine kinase 3 (LMTK3) (Kd=2.5 ?M)?that acts by degrading LMTK3 via the ubiquitin-proteasome pathway. LMTK3-IN-1 shows anticancer activity in a variety of cancer cell lines and in vivo BC mouse models. LMTK3-IN-1 induces apoptosis in BC cell lines at 10-20 ?M.