PIK3R1 and brain ischemia: Furthermore, GRb1 significantly inhibited the expression of the proapoptotic genes Bax, Bad, and caspase-3 (Yang et al., 2008; Gao et al., 2010), upregulated Bcl-2 and the ratio of Bcl-2/Bax in vivo and in vitro (Yuan et al., 2007; Yang et al., 2008), increased the expression of glial-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) (Yuan et al., 2007; Gao et al., 2010), and thus prevented neuronal death induced by cerebral ischemia.