SHH and medulloblastoma: Besides, expression analysis of the miR-17-92 cluster showed that three miRNAs (miR-92, miR-19a, and miR-20) are over-expressed only in human medulloblastomas with a constitutively activated Sonic Hedgehog/patched (SHH/PTCH) signaling pathway, suggesting the role of the miR-17-92 cluster in the formation of aberrant SHH/PTCH pathway driven medulloblastomas[32].