Overview: Recently it has been established that miRNA activity on the target gene can be influenced by the presence or absence of other competing endogenous (ceRNA) mRNAs that contain shared MREs. These miRNA activity modulators can act as a sponge, absorbing and releasing miRNA based on the level of the transcript. The competing endogenous RNA database (ceRDB), lists potential MRE containing genes that can act in a sponge like fashion for a given mRNA based on a set of scoring and ranking criteria.