Disclosed are methods for identifying therapeutics and diagnosis. In general, methods for identifying therapeutic agents directed to calcium flow are disclosed. Also provided are methods for diagnosis of breast cancer and/or a predisposition to breast cancer and methods of treatment of breast cancer. The methods include identifying therapeutic agents which modulate a CRAC channel and/or a glycoprotein activator of a CRAC channel. Also provided are diagnostic methods that ultilise a CRAC channel and/or a glycoprotein activator of a CRAC channel.