CYP27A1 and infection: Thus, SV40 transport is shown to proceed from caveosomes, although this is not obligatory for infection [56,99] so there may be further sorting in early endosomes; ricin and CTx transport is depicted as STx-like from early endosomes to the TGN, although there may be multiple routes; and CTx and ricin are depicted as following a single route from the TGN to the ER, but this is poorly characterised, without known markers.