To study the internalization of anetumab ravtansine and its localization in cancer cells, the targeting antibody moiety of anetumab ravtansine (anetumab, MF-T) was coupled to a pH-sensitive fluorescent dye and incubated with HT29 human colon adenocarcinoma cells stably transfected with mesothelin (HT29-MSLN). This evidence concerns the gene MSLN and colon adenocarcinoma.