Withdrawals survival data

Let us suppose that the inimical process can be applied to a population of bacteria in an incremental manner. Initially and after various periods of exposure we can withdraw samples from the population and count the number of viable bacteria present. When we plot these data as a survival curve on arithmetic axes we get the form of Fig. 2a. The relationship of survivors to time of exposure shows an initial rapid decline and then levels out and becomes asymptotic to the time axis. If we were to convert the survivor data to logarithms and then plot these logarithmic data against time of exposure we would obtain a straight-line relationship (Fig. 2b). This is the general form for exponential or logarithmic survival curves. 

Although the PI3-K/Akt pathway is a promoter of cell proliferation and cell survival, under defined conditions, the PI3-K/Akt pathway is also involved in promoting cell death. The activation of PI3-K/Akt has been observed in some experimental systems on induction of apoptosis by selected stimuli like CD95, cisplatin, arsenite, TNF, serum withdrawal, hypoxia (Aki et al. 2001, 2003 Bar et al. 2005 Lee et al. 2005 Lu et al. 2006 Nimbalkar et al. 2003 Ono et al. 2004 Shack et al. 2003). Recent data also indicate that apoptin, a viral protein that selectively kills cancer cells, requires for its toxicity both PI3-K/Akt activation and the phosphorylation by CDK2 (Maddika et al. 2008a). 

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