Tubulin polymerization-IN-72 (Compound 4a4) is an anticancer agent that acts as a tubulin polymerization inhibitor. It inhibits tubulin polymerization by binding to the colchicine site, leading to cancer cell arrest in the G2/M phase and inducing their apoptosis ( Apoptosis ). Tubulin polymerization-IN-72 has an IC 50 of 0.4-2.7 nM against cancer cells.