In support of this, the RT-qPCR analysis showed that miR-21 expression is moderately upregulated in low-grade astrocytoma and even highly upregulated in malignant glioblastoma, while high expression of CASC2 in tumors might be responsible for the decrease of miR-21 expression. The gene discussed is CASC2; the disease is astrocytoma (excluding glioblastoma).