A cocktail of five phosphatase inhibitors for the inhibition of acid and alkaline phosphatases as well as protein tyrosine phosphatases (PTPs). Suitable for use with cell lysates and tissue extracts, including samples containing detergents. Provided as a set of five 1 ml vials containing the following components: Imidazole (200 mM), Sodium Fluoride (100 mM), Sodium Molybdate (115 mM), Sodium Orthovanadate (100 mM), and Sodium Tartrate Dihydrate (400 mM).