CDKN1B and pituitary gland adenoma: Mutations in PTMs of histones, for example, significant down-regulation of the MLL-p27 (Kip1) pathway in pituitary adenomas and up-regulation of BMI1, which is a component of polycomb repressive complex 1 (PRC1) in MB, are known to have a high rate of mortality or poor survival [175, 176].