GRN and ductal breast carcinoma in situ: Immunohistochemistry (IHC) studies of formalin-fixed paraffin-embedded (FFPE) tumor specimens demonstrated that GP88 tumor tissue expression was low or negative in normal mammary tissues and lobular carcinoma whereas it was elevated in ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) tissues [21].