Stattic is a small molecule that selectively inhibits STAT3 activation, dimerization, and nuclear translocation by preventing the binding of tyrosine-phosphorylated peptide motifs to the STAT3 SH2 domain (IC₅₀ = 5.1 μM at 37°C). Displays selectivity over STAT1, STAT5, c-Myc/Max, Jun/Jun and Lck. At 10 μM, stattic induces apoptosis in STAT3-dependent breast cancer (MDA-MB-231 and MDA-MB-435S) cell lines.