CTSB and thyroid gland carcinoma: This localization pointed to a transport defect of this thyroid carcinoma cell line, because the cathepsin B pattern observed by expression of the GFP-tagged protease was reminiscent to the predominant reticular staining pattern with only few vesicular structures that were immunolabeled in KTC-1 cells with cathepsin B-specific antibodies (see, Figure 4).