CD44 and neoplasm: As a first step to validating these findings, independent siRNAs were used to silence the expression of IL-6, BRCA1, ORC5L, RFC3, POLS, ERCC8 and RPA2 in H1650-M3 and H1650 cells, as well as in seven additional tumor-derived cell lines characterized by low (A549, MCF7 and BT474) or high (NCI-H23, PC9, MDA-MB-435S and MDA-MB-231) content of CD44+/CD24− cells (Figure 1B and Figure 1—figure supplement 2).