So far only PP2A, calcium/calmodulin and PKAmediated signaling pathways have been shown to be
essential for excystation (Abel et al., 2001; Reiner
et al., 2003; Lauwaet et al., 2007b). Inhibitors of PP2A
and PKA blocked excystation when added to cysts in
the in vitro stage that mimics their passage through
the stomach. In addition, excystation of gPP2Ac antisense cysts was decreased compared to controls and
the PP2A inhibitor okadaic acid inhibited resumption
of motility when added to the later stage of excystation (Lauwaet et al., 2007b). The highly conserved
calcium binding protein calmodulin localizes to the
basal body area in Giardia trophozoites and inhibitor
studies showed that intracellular calcium levels and
calmodulin are important