To further characterize molecular pathways which may play a critical role in the mesenchymal and epithelial states, we investigated the transcriptional landscape using RNA-Seq in cancer cells with primarily epithelial-like BCSCs (BT474, HER2+, trastuzumab sensitive) or mesenchymal-like BCSCs in PTEN-deficient trastuzumab resistant cells (BT474-PTEN-LTT). This evidence concerns the gene ERBB2 and cancer.