Phosphatase microinjection

It should be noted that microinjection of C3 into quiescent serum-starved Swiss 3T3 cells is not without effect. Despite the cells having few if any actin stress fibres, or visible vinculin staining in focal adhesions, C3 causes cells to round up and to become detached from the underlying substrate. This indicates that there is, even in serum-free conditions, a low basal activity of Rho, perhaps maintained by a tyrosine kinase/phosphotyrosine phosphatase cycle upstream of Rho (Nobes ef al., 1995). Interestingly, the cell rounding and detachment induced by injection of C3 into quiescent cells is inhibited by coinjection of activated Rac or by addition of PDGF (5ng/ml), which... 

Microinjection of Cdc25 protein phosphatase into Xenopus prophase oocyte activates MPF and arrests meiosis at metaphase I. Biol Cell 82(l) ll-22. 

Tonks NK, CicireUi MF, Diltz CD, Krebs EG, Fischer EH. 1990. Effect of microinjection of a low-Mr human placenta protein tyrosine phosphatase on induction of meiotic cell division in Xenopnis oocytes. Mol Cell Biol 10(2) 458-463. 

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