The purpose of this project is to identify the substrates that are specific for B'delta regulatory subunit. For this purpose, we have generated two doxycycline-inducible stable cell lines (OE and RE) that express B'delta. In the OE cell lines, B'delta is overexpressed without downregulation of the endogenous regulatory subunits. On the other hand, in the RE cell lines, B'delta is overexpressed concurrently with a downregulation of the endogenous regulatory subunits. To stimulate protein phosphorylation, we used isoproterenol, a beta-adrenergic agonist that is known to induce the PKA-mediated phosphorylation and activation of the B'd.