Although limited information is available on the biological function of STX12 (also known as STX13), it was first identified as being localized in the endosome [39] and involved in the SNARE-dependent trafficking of matrix metalloproteinases, thereby remodeling the extracellular matrix and modulating the cell invasion activity of human fibrosarcoma cells [28,40]. Here, STX12 is linked to fibrosarcoma.