ABCB1 and ductal breast carcinoma in situ: Further, we identified four novel genes (ABCB1, FOXC1, PPP2R2B and PTEN) that were found to be already aberrantly methylated in DCIS (Ductal carcinoma in situ), a pre-invasive stage of breast cancer [4] and that were also found to be methylated in the locally advanced breast cancers [3].