This invention relates to methods for activation of T cell protein tyrosine phosphatase (TCPTP) and for inhibiting tyrosine kinase signalling in an individual. The invention concerns a method for preventing or treating a disease or disorder in an individual, wherein said disease or disorder is curable by inhibiting tyrosine kinase signalling, and a method for preventing cancer, or preventing or inhibiting cancer growth, invasion or metastasis in an individual, based on activating T cell protein tyrosine phosphatase (TCPTP). The invention also concerns pharmaceutical compositions useful in the methods.