MicroRNAs (miRNAs) are a class of small, non-coding regulatory RNAs that bind to mRNAs to cause degradation or inhibition of translation for the targeted mRNAs.

Genetic variations in microRNA seed regions or binding sites can disrupt the interaction between microRNAs and mRNAs, rewire the microRNA regulatory networks, and cause various diseases.

PolymiRTS (Polymorphisms in microRNAs and Target Sites) is a database of DNA variations in microRNA seed regions and microRNA target sites.

MicroRNAs can bind to many types of RNAs, including mRNA, circular RNAs (circRNAs), and long noncoding RNAs (lncRNAs).

These RNAs are called competing endogenous RNAs (ceRNAs) because they compete for the binding of microRNAs.

CeRNAs can regulate the abundance of microRNA-targeted mRNAs by competing for microRNA binding.

Aberrant microRNA-ceRNA interactions are associated with many types of cancers.

SomamiR is a database of cancer somatic mutations in microRNAs and their target sites that potentially alter the interactions between microRNAs and ceRNAs, including mRNAs, circRNAs, and lncRNAs.

The CTCF protein functions as a genomic insulator, setting boundaries to block interactions between enhancers and promoters. It is also important for the 3D organization of the genome.

The CFCF-binding site database is a collection of known CTCF binding sites.

It also provides tools for predicting and performing functional analysis of CTCF binding sites.