PVT1 and breast cancer: Inhibition of miR-1204 reduced proliferation of group 3 MB cells at a level comparable to MYC knockdown, while an MB cell line with neither MYC amplification nor detectable PVT1-MYC fusion gene was unaffected by miR-1204 knockdown.28 PVT1 stabilizes MYC to promote tumorigenesis, and the PVT1 locus is often amplified in breast cancer.56 However, PVT1 is also frequently disrupted by recurrent translocations or deletions in many cancer types, including MB, suggesting that it may have additional regulatory functions.