BRD4 and breast carcinoma: In normal tissues, the four internal enhancers of PVT1 are preferentially contacted by the PVT1 promoter; thus, BRD4 will preferentially occupy the PVT1 promoter, reducing the occupation of BRD4 at the MYC promoter and decreasing the transcription of MYC. Therefore, the PVT1 promoter can act as a tumor suppressor DNA element of MYC. In human breast cancer and malignant lymphoma, the PVT1 promoter is mutated.