PTEN and hepatocellular carcinoma: miRNA microarray analysis identified miR-21 to be the most highly overexpressed miRNA in human HCC, and it was demonstrated that it augments the proliferation and invasion of human HCC cells by targeting phosphatase and tensin homolog (PTEN), a negative regulator of the oncogenic phosphatidylinositol-3-kinase/AKT serine/threonine kinase (PI3K/AKT) pathway [87].