PDE4B and serum lipopolysaccharide activity: The inhibition of PDE7A seems to display an additional anti-inflammatory effect, as a strong inhibitor of PDE7A – GRMS-55 demonstrated ~5.5 and ~4.0 times lower IC50 values in LPS-induced endotoxemia and CIA, respectively, than (±)-LSF, which is only a ~2.0 times weaker PDE4B inhibitor than GRMS-55.