RIPK1 and breast cancer: For example, researchers have found that RIPK1 inhibitors do not suppress tumor growth in genetically engineered mice models of pancreatic cancer.265 And it has been shown that in mouse mammary tumors, knockout of ZBP1 and MLKL, but not RIPK1, reduces lung metastasis.266 We may therefore conclude that RIPK1 regulates tumor growth through its scaffolding function rather than its kinase activity.260