CSN2 and cystic neoplasm: There was no significant difference in the expression of Csn2 and Csn1s2a between PyMT tumors and the solid tumors from PyMT/S14−/− mice (Figure 5I); however, the cystic tumors that formed in PyMT/S14−/− mice had lower expression of Csn2 and Csn1s2a than those from PyMT mice or than the solid tumors from PyMT/S14−/− mice, indicating an altered differentiation profile in a subset of PyMT/S14−/− tumors.