CST3 and neoplasm: Immunohistochemically, cystatin C protein was stained intracellularly in the cytoplasmic compartment of tumour cells in a variety of cancer types (Lignelid and Jacobsson, 1992; Lignelid et al, 1997; Yoshimura et al, 2000; Gaumann et al, 2001; Hansen et al, 2001; Yano et al, 2001).