miRNA microarray identified miR-21 to be the most highly overexpressed miRNA in human HCC and it was demonstrated that it augments proliferation and invasion of several human HCC cells, such as HepG2, PLC/PRF-5, SK-HEP-1, and SNU-182, by targeting phosphatase and tensin homolog (PTEN), a negative regulator of oncogenic PI3K/AKT pathway [81]. The gene discussed is PTEN; the disease is hepatocellular carcinoma.