Polypyrimidine tract-binding protein, also known as PTB or hnRNP I, is an RNA-binding protein. PTB functions mainly as a splicing regulator, although it is also involved in alternative 3' end processing, mRNA stability and RNA localization.[1] Two 2020 studies have shown that depleting PTB mRNA in astrocytes can convert these astrocytes to functional neurons.[2][3] These studies also show that such a treatment can be applied to the substantia nigra of mice models of Parkinson's disease in order to convert astrocytes to dopaminergic neurons and as a consequence restore motor function in these mice.