PTPA and hyperhomocysteinemia: We have reported in vivo that low folate status (Sontag et al., 2008) and hyperhomocysteinemia (Sontag et al., 2007), lead to down regulation of expression levels of LCMT1, PP2A methylation, and PP2A holoenzymes containing the regulatory Bα (or PPP2R2A) subunit (PP2A/Bα).