HIF1A and breast cancer: miR-21 targets phosphatase and tensin homolog deleted on chromosome ten (PTEN) and induces angiogenesis through the upregulation of HIF-1α and VEGF expression via the activation of AKT (RAC-Alpha Serine/Threonine-Protein Kinase) and extracellular regulated kinase (ERK) pathways, as demonstrated in prostate cancer cell lines [55], glioma [56], pancreatic cancer cell lines [57], breast cancer [58], and HCC [59].