CCND1 and neoplasm: Examining mice at 3-5 months of age, we observed an obvious border between the malignant and pre-malignant parts of the pineal gland [Figure 5A, left]; this border disappeared as the tumor infiltrated the whole pineal gland [Figure 5A, right], and SAHF were lost in the emerging Irbp-Cyclin D1, p18Ink4c -/- tumor [Figure 5B].