SD-436 is a highly selective and efficacious STAT3 PROTAC degrader ( DC 50 : 0.5 μM), with IC 50 of 19 nM ( STAT3 ), 270 nM ( STAT1 ), 360 nM (STAT4), >10 μM ( STAT5 ) and >10 μM ( STAT6 ). SD-436 promotes ubiquitination and degradation of STAT3 , and induces tumor regression. SD-436 can be used for tumor research, such as leukemia and lymphoma (Pink: STAT3 ligand ; Blue: E3 ligase ligand ; Black: linker.