In a recent issue of Cell, four papers described regulatory interactions among messenger RNAs (mRNAs) that share target sequences for the same microRNAs (miRNAs) (Cesana et al., 2011; Karreth et al., 2011; Sumazin et al., 2011; Tay et al., 2011). The authors state that these mRNAs, dubbed ‘‘competing endogenous RNAs (ceRNAs),’’ define a new layer of regulation of miRNA activity that has only re...
