PER1 and lymphoma: Bmal1+/−, Cry- and Per-mutant mice all showed increased risk of ulcerative dermatitis and hyperplasia in the salivary gland, preputial gland, liver and uterus as well as spontaneous lymphoma, liver and ovarian tumor development, although spontaneous tumors in Cry-mutants were mostly identified after 50 weeks of age, later than that of Per1−/−;Per2m/m and Per2−/− mice (Fig. 1a, Table 1, Fig. S1a and data not shown).