CDKN1A and frontotemporal dementia: Furthermore, FTD has been shown to activate the p53 pathway30,31, a pathway whose activation upon DNA damage can lead either to induction of p21 (CDKN1A) and subsequent cell cycle arrest or to apoptosis mediated by p53 upregulated modulator of apoptosis (BBC3) and TP53-inducible gene 3 (TP53I3)31.