To investigate the molecular mechanism on the treatment efficacy of irradiation on cysts, the expressions of five key genes — namely thioredoxin peroxidase (TPX), heat shock protein 70 (HSP70), EPC1, caspase-3, and growth arrest and DNA damage-inducible protein 45 (Gadd45) — involved in cyst development were determined. This evidence concerns the gene GADD45A and cyst.