PCR analysis of Edg receptor expression. The expression of Edg family receptors in primitive hematopoietic cells was assessed by semiquantitative PCR (A). For details of cells see legend to Figure 1. BM indicates whole bone marrow. Samples from various tissues were used to obtain positive controls for the PCR experiments. Results are shown for one representative experiment of 3 with 3 different cell populations. Panel B illustrates the semiquantitative nature of the RT-PCR. It shows the amalgamated results of RT-PCR reactions from a dilution series of 10%, 20%, 50%, and 150% of cDNA for each primer combination. Results are the mean ± SEM of at least 3 separate experiments.