Activation of the proapoptotic function of BAD by phosphatase in IL-3–dependent FL5.12 cells is regulated by 14-3-3 binding.

In the presence of survival factor IL-3, BAD is phosphorylated and binds 14-3-3. Dephosphorylated BAD is also present, presumably because of constitutively active phosphatases. We propose that an apoptotic stimulus such as IL-3 withdrawal destabilizes the 14-3-3–BAD interaction, increasing the susceptibility of BAD to PP2A or a PP2A-like phosphatase, promoting BAD dephosphorylation and cell death.