Background:

SQ22536 is an effective adenylate cyclase (AC) inhibitor.
SQ22536 (SQ22,536) effectively inhibits the effect of forskolin with respective IC50 values of 5 μM.Preincubation with graded concentrations of SQ22536 reveals that both SQ22536 effectively inhibits PACAP-induced reporter gene activation with approximate IC50 value of 5 μM. SQ22536 more potently inhibits forskolin-induced Elk activation (IC50=10 μM) than 8-Br-cAMP-induced Elk activation (IC50=170 μM). Most notably, there are substantial differences in the reported potencies of SQ22536 to inhibit the activities of recombinant AC5 and AC6, with respective IC50 values of 2 μM and 360 μM. At a greater concentration (500 μM), SQ22536 significantly inhibits neurite elongation due to either forskolin or 8-Br-cAMP[1].
Reference:
[1]. Emery AC, et al. A new site and mechanism of action for the widely used adenylate cyclase inhibitor SQ22,536. Mol Pharmacol. 2013 Jan;83(1):95-105.