POSTN and neoplasm: Importantly, knockdown of periostin reversed many cellular and molecular changes induced by chemotherapy: reduction of the mesenchymal cell population identified as being CD44high/CD24low, CD44high/E-cadherin−, or CD44high/vimentin+ cells (Fig. 5C; Supplementary Fig. S4A), decrease of chemotherapy-induced proliferation of mesenchymal tumor cells (Fig. 5D–G).