CASC2 and cancer: MicroRNAs (miRNAs) are another group of non-coding RNAs, which are important posttranscriptional regulators.10,11 MiRNAs play crucial roles in various biological processes, and aberrant miRNAs expression is associated with many kinds of diseases, including cancers.12 For instance, miR-18a and miR-21 are found to be over-expressed in NSCLC.13,14 It is well known that lncRNAs may interact with miRNAs and regulate the expression of their target miRNAs.15 Moreover, miR-18a and miR-21 have been demonstrated to be the targets of CASC2.16,17