Yet, the almost complete abolishment of Erk activity observed in the hepatic-Erk1R84H mouse model, the Erk1R84S- and Erk1R84H-transformed cells and in cancer-derived cell lines suggest that for cancer development the “Goldilocks principle” does not lead to some intermediate Erk activity, but rather to a minimal activity. This evidence concerns the gene MAPK1 and cancer.