M. viscosa infection suppressed the expression of NADPH oxidase 4 (nox4) at the skin lesion site of Atlantic salmon (Mv-At) compared to the other groups, whereas fibroblast growth factor receptor 2 (fgfr2) down-regulation was only seen between the Mv-At group compared with the control and Mv-N groups (Fig. 4J,K). This evidence concerns the gene NOX4 and neoplasm.