RT-PCR and Southern blotting. Total RNA obtained from platelets and Hep G2 cells was subjected to RT-PCR and Southern blotting using primers specific for a 438-bp fragment of PCI-cDNA. A PCI-cDNA fragment inserted into the plasmid vector pBluescript II KS (+/−) phagemid was also amplified by PCR with the same primers. Additionally, a negative control was performed by amplifiying a sample without platelets. After blotting, the membrane was incubated with a³²P-labeled PCI-cDNA fragment and subjected to autoradiography as described in Materials and Methods.