Absence of PAR-3 and GPIb in B16F10 cells. RT-PCR are shown for wild-type B16F10 (lanes 1, 3, and 5) and mouse spleen (lanes 2, 4, and 6). HPRT was used as an internal standard in lanes 1 through 4 (expected product, 284 bp). Lanes 1 and 2 demonstrate the respective absence and presence of PAR-3 in B16F10 versus mouse spleen for the 341-bp PAR-3 primer product. Similar results are shown for lanes 3 and 4 using PAR-3 primers with the expected 397-bp product. Lanes 5 and 6 demonstrate the respective absence and presence of GPIb versus mouse spleen for the expected 290-bp product.