Human peripheral monocytes, macrophages, and dendritic cells do not express protease-activated receptor 4 mRNA. RT-PCR analysis did not detect PAR4 mRNA expression on either CD14⁺ monocytes or macrophages or dendritic cells. Human platelets were used as a positive control. GAPDH was used for normalization. M indicates marker. Results of 1 of 3 independent experiments are shown.