Inhibition by guanosine cyclic monophosphate (cGMP) analogues of uptake of [3H]3′,5′-cGMP without stimulation of ATPase activity in human erythrocyte inside-out vesicles11Abbreviations: 3′,5′-cGMP, guanosine 3′,5′-cyclic monophosphate; 2′,3′-cGMP, guanosine 2′,3′-cyclic monophosphate; N-mb-cGMP, N2-monobutyryl guanosine 3′,5′-cyclic monophosphate; O-mb-cGMP, 2′-O-monobutyryl guanosine 3′,5′-cyclic monophosphate; Db-cGMP, N2,2′-O-dibutyryl guanosine 3′,5′-cyclic monophosphate; Br-cGMP, 8′-bromo guanosine 3′,5′-cyclic monophosphate; Rp-cGMPS, Rp-monophosphorothioate guanosine 3′,5′-cyclic monophosphate; Sp-cGMPS, Sp-monophosphorothioate guanosine 3′,5′-cyclic monophosphate; 3′,5′-cAMP, Adenosine 3′,5′-cyclic monophosphate; and MRP, multidrug resistance protein.