PceRBase: a database of plant competing endogenous RNA. miRSponge: a manually curated database for experimentally supported miRNA sponges and ceRNAs. lnCeDB: database of human long noncoding RNA acting as competing endogenous RNA. RNAcentral: the non-coding RNA sequence database. miRBase: the microRNA database. NCBI Gene: database for providing the information about genes.