CA-4. Instead of inhibiting tubulin polymerization, these CA-4 derivatives were able to stimulate tubulin polymerization. Flow cytometry revealed that compound 8c4 arrested A549 cancercells in the G2/M phase and resulted in cellular apoptosis. Further immunofluorescence assays revealed that compound 8c4 induced mitoticarrest in A549 cells through disrupting microtubule dynamics. In addition, compound