KRAS and Acanthamoeba infectious disease: In this study, we found that Acanthamoeba infection mainly affected the expression level of the K-Ras gene in HCECs, and Western blot analysis showed that trophozoites could also increase the phosphorylation levels of Raf, Erk1/2 and p53 in HCECs; taken together, this indicates that Acanthamoeba could activate the Ras/Raf/ERK/p53 signalling pathways of host cells.