Results SFK inhibitor SU6656 inhibits proliferation and induces polyploidy and senescence in E14/T mouse embryonic stem cells In addition from what was once reported on the inhibitory effect of the SFK inhibitor SU6656 on mouse embryonic stem cell self restoration, prolonged contact with SU6656 also induces an cell morphology in mES cells. The cells become enlarged and flattened and when stained with Hoechst 33342 giant nuclei are shown by the cells with repeated occurrences of abnormal metaphases and reduced cytokinesis. chk2 inhibitor Karyotyping of the SU6656 open cells showed an increased quantity of the conventional euploid 40 chromosomes. Total cellular number examination with time showed no proliferation up to 96 h of constant SU6656 exposure, suggesting that the result is immediate. Additionally, after 72 h the protein levels of proliferating cell nuclear antigen, which ismainly expressed during the DNA synthesis stage of the cell cycle, were significantly reduced. After 72 h of culture using the recommended levels of SU6656 several cells have detached, implicating cell death. However,most cells do survive and seemingly enter senescence, staining positive for senescence connected B galactosidase activity at pH 6. 0. Elevated Organism levels of the cyclin dependent kinase inhibitors p16INK4a and p21WAF1, which have been implicated in cellular senescence, were upregulated after 48 h with SU6656 as shown by RT PCR for p21 and p16. Moreover, an additional 48 h of treatment with Arabinosyl cytosine, a chemotherapeutic antimetabolite that causes DNA fragmentation during reproduction and subsequent cell death during mitosis, didn’t have any influence, further suggesting that the SU6656 treated cells have entered the state of senescence. Actually, the cells were checked for an additional 6 days after treatment but didn’t show any sign of neither cell division or cell demise (-)-MK 801 but stained positive for senescence associated W galactosidase activity. To assesswhether the effects described above are specific to mES cellswe more revealed other cell lines to SU6656. Interestingly,we observed similar phenotypic responses in the conventional mouse mammary gland and the mouse embryonic fibroblast cell line NIH3T3 epithelial cell line NMuMG Fucci, confirming that the effect isn’t cell specific. Similar results were seen through the period of the recommended levels. More interestingly, we could also discover a similar result in MEF cells deficient in Src, Yes and Fyn created frommouse embryos harboring practical null mutations in both alleles for the Src family protein tyrosine kinases, Src, Yes and Fyn, and there have been no difference within their reaction compared to similar cells with an reintroduced d Src.