SRGN and metastatic malignant neoplasm: Lung is the major site for metastasis in the MMTV-PyMT model[23, 31, 32] and since serglycin has been implicated in aggressive metastatic cancer[15, 16] we first analysed the number of lung metastases in littermate PyMT+ SG+/- and SG-/- mice, respectively.