BRCA1 and cancer: Also positively associated with at least one of the 3 methylation markers is the upregulation of cancer proliferation signaling pathways including: PTEN (PTEN dependent cell cycle arrest and apoptosis), P53 (p53 Signaling Pathway), P27 (Regulation of p27 Phosphorylation during Cell Cycle Progression), RB (RB Tumor Suppressor/Checkpoint Signaling in response to DNA damage), ATRBRCA (Role of BRCA1, BRCA2 and ATR in Cancer Susceptibility), and MTOR (mTOR Signaling Pathway).