Effects of nifedipine (NIF) on phorbol myristate acetate (PMA)-induced protein phosphorylation in monocytes as detected with the fluorescent probe ProQ-Diamond. (a, b) Representative gels of phosphorylated protein from homogenates of monocytes from healthy donors, treated with the indicated concentrations of nifedipine (a, b) or calphostin (CAL) (b) for 30 min and then stimulated with 100 nM PMA for 10 min. Right panels show a representative densitometric analysis of 10 protein bands (molecular masses from 15 to 60 kDa) that were strongly phosphorylated in the presence of PMA. (c) Effects of nifedipine on the cytosolic fraction of control monocytes treated in vitro with the indicated concentrations of nifedipine for 30 min before stimulation of protein kinase C with a mixture of calcium and diacylglycerol. Results are the net phosphorylation induced by PMA, expressed relative to the PMA lane (taken as 100%).