CD44 and breast cancer: Our finding that HIF-1α is related to CD44+CD24-/low immunphenotype in breast ductal carcinomas could indicate that a maintained hypoxia state in breast cancer could facilitate the maintenance of cancer stem cells in these tumors, corroborating the finding that CD44+CD24-/low positive tumors have a worse prognosis when compared to non- CD44+CD24-/low tumors.