ANPEP and rhabdomyosarcoma: In the present study, the relative abundance of Helicobacter in rhabdomyosarcoma-bearing APN knockout mice was significantly increased compared with that of the rhabdomyosarcoma-bearing wild-type mice, implying the increase of Helicobacter may be beneficial to the protection of APN deficiency, which is associated with increasing the release of extracellular products such as urease and HtrA serine proteases.