CDKN1B and neoplasm: Recently, Pirh2, a RING finger type E3 expressed both in the nucleus and cytoplasm, has also been found to target p27Kip1 for degradation in a panel of tumor cell lines, including T98G (glioblastoma), MCF7 (breast carcinoma), Colo320DM (colon carcinoma), and HeLa cells (uterine cervical carcinoma) [16], [17].