['To determine whether protein kinase C (PKC) has any effect on the expression of cyclinD1, a key regulator of growth control and G1/S transition, and to investigate the underlying molecular mechanisms of PKC involving the remodeling of the asthmatic airway smooth muscle (ASM).', 'The treatment of synchronized ASM cells from asthmatic rats with PKC-specific agonist phorbol 12-myristate 13-acetate (PMA) and antagonist 2-{1-[3-(amidinothio) propyl]-1Hindol-3-yl}-3-(1-methylindol-3-yl) maleimide methanesulfonate salt (Ro31-8220) was followed by the proliferation assay. PKCalpha and cyclinD1 expressions in ASM cells (ASMC) were detected by RT-PCR and Western blotting. The relation between PKCalpha and cyclinD1 was assessed by linear regression analysis. The effect of the construct recombinant plasmid pcDNA3.1-antisense cyclinD1 (pcDNA3.1-ascyclinD1) on the proliferation of ASMC was found to be induced by PMA.', 'The data showed phorbol ester-dependent PKCalpha promoted the proliferation of ASMC. The closely-positive correlation existed between the expression of PKCalpha and cyclinD1 at the transcriptional (r=0.821, P<0.01) and translational (r=0.940, P<0.01) levels. pcDNA3.1-ascyclinD1 could inhibit the proliferation of ASMC. pcDNA3.1-ascyclinD1 almost completely attenuated the PMA-induced proliferation effect as Ro31-8220+pcDNA3.1.'] Does pKC promote proliferation of airway smooth muscle cells by regulating cyclinD1 expression in asthmatic rats?