Figure 5. The levels of cGMP induced by retGC1 are regulated by GCAP1-WT/D144G in vitro. A: The levels of cyclic guanosine monophosphate (cGMP) induced by retGC1 in the human embryonic kidney (HEK)-293 cells are measured in the presence of GCAP1-WT/D144G. The free Ca²⁺ concentration is 2.5 μM. The mock-transfected group was used as control. B: The levels of cGMP stimulated by transfected retGC1 in the HEK-293 cells were regulated by purification of GCAP1-WT/D144G. The free Ca²⁺ concentration was 2.5 μM. The operation was repeated three times. Error bars were standard deviation.