Reserpine-sensitive SP cells represent a subset of primitive cell phenotypes. All values are expressed as a mean of 5 separate experiments. Expression of cell markers is displayed as percentage of SP. The SP was enriched for the primitive cell phenotypes KLS, KLS/CD31⁺, KTLS, and KTLS/CD135^neg Approximately half of SPs were KLS/CD34⁺. Displayed for comparison are the small amounts of each antigen-defined subset that fell within the SP gate.