In addition, cathepsin B-containing vesicles were localized to the basolateral poles as highlighted by immunostaining of the basal plasma membrane domains of neoplastic cells in PTC (Figure 2C, arrowheads) and of the lateral plasma membrane domains in FTC tissue (Figure 2F, arrowheads), indicating non-directed cathepsin B secretion into the extrafollicular space. This evidence concerns the gene CTSB and thyroid cancer, nonmedullary, 2.