RNA binding proteins (RBPs) such as heterogeneous nuclear ribonucleoprotein (hnRNP), serine-arginine (SR), and FUS protein [42,43], as well as splicing regulators such as NF110 and NF90, Muscleblind, and NOVA2 can bind to intronic sequences flanking circularized exons and stabilize CIS pairs enhancing the production of circRNA [44,45,46]. This evidence concerns the gene ILF3 and in situ carcinoma.