Figure 1.

Survival pathways controlled by Tax. A growing body of evidence suggests that the anti-apoptotic effect of Tax is mediated by the activation of distinct signaling cascades, including NF-κB, PI3K/Akt and MEK/ERK1/2. Both canonical and non-canonical NF-κB pathways are activated by Tax, and control the expression of numerous survival genes; the PI3K/Akt pathway, also activated by Tax, acts by inhibiting the pro-apoptotic protein Bad, by activating the NF-κB pathway and inducing CREB phosphorylation; the Raf/MEK/ERK1/2 pathway is engaged by Tax through Ras activation. RasGTP can also induce PI3K activation; down modulation of PTEN expression by Tax leads to both Akt activation and increased levels of phosphorylated CREB in the nucleus.