CA 432 was 10 fold more effective than CA 4 in the HT 29 cells suggesting a possible practical benefit of the ethylene bridge azetidinone alternative. A adenocarcinoma cell line CT 26 and the fibrosarcoma cell line Geneticin distributor were selected for further studies to discover the molecular mechanism of combretastatin induced cell death in colon carcinomas. In agreement with current publications, we confirmed that tubulin is the molecular target of both CA 4 and its artificial by-product, cells were derived by CA 432 in both HT 1080 and CT 26 colon cancer. The result of CA 4 and CA 432 on the cell cycle over time was next established by flow cytometric evaluation of the DNA content of propidium iodide stained cells. As shown in Fig. 2, a significant G2M arrest was induced by both compounds at 8 h. In HT 1080 cells a from G2M cell cycle arrest resulted in a period dependent increase in cell death as dependant on an increase in the percentage of cells in sub G1. On the other hand, in CT 26 cells a release from G2M gave two different outcomes, polyploidy and cell death. CA 4 and CA 432 caused both cell death and polyploidy in Caco 2 cells subsequent to mitotic launch. Induced cell death is compounded by both however not polyploidy in HT 29 cells at cytotoxic concentrations. In summary, prolonged contact with combretastatins could ultimately cause cell death or continuing DNA replication without cell division in cancer of the colon cells. Apoptosis, Autophagy and oncotic/necrotic Skin infection would be the principle pathways of programmed cell death, although others have now been identified. Apoptosis is characterised by different morphological modifications including chromatin condensation and cell shrinkage and apopto tic prints including DNA fragmentation and caspase activation. The traditional top features of Type I cell death were seen in HT 1080 cells confronted with CA 4 and CA 432. Like, the morphological options that come with apoptosis including chromatin condensation, cell shrinkage and the apoptotic Lonafarnib price bodies were noticeable in cytospin preparations of CA 4 and CA 432 treated HT 1080 cells but were absent in get a handle on cells. Furthermore, the activation of caspases by the combretastatins in HT 1080 cells was confirmed by a fluorescent based quantitative assay, the disappearance of cleavage of the caspase 3 substrate and total size caspase 3, poly polymerase by western blotting. Furthermore, pre therapy of HT 1080 cells with the general caspase inhibitor Z VAD FMK significantly inhibited combretastatin induced cell death. Collectively, these results suggest combretastatins encourage a dependent Type I cell death in the fibrosarcoma HT 1080 cells. In comparison, CT 26 adenocarcinoma cells exposed to combretastatins increased in cell size and contained numerous nuclei and vacuoles and the cell death observed was caspase separate.