PRRT2 and systemic sclerosis: In this report we show that, first, ex vivo monocytes from patients with SSc not treated with calcium-channel blockers produce more O2•- than control monocytes; second, nifedipine (60 mg/day) strongly inhibits the ability of monocytes to produce O2•- ex vivo; and third, nifedipine inhibits O2•- production by healthy monocytes in vitro, a property associated with the inhibition of PKC-dependent protein phosphorylation and PKC activity.