PTPN1 and heart failure: PTP1B is overexpressed in human and murine heart failure: For example, a significantly increased PTP1B activity was detected in hypertrophic hearts of rats after bandings as well as in left ventricular tissue specimens of patients with systolic dysfunction undergoing aortic valve replacement (194), and we have shown in mice that cardiac hypertrophy is associated with elevated cardiac PTP1B protein levels (195).