Representative patterns of light and dense RBC recovery as a function of time after onset of Ca²⁺ pump activation. The ordinate reports the percent of RBCs harvested from the top of the DEP oil (●, δ less than 1.117) or from the pellet under the oil (○, δ more than 1.117) after secondary incubation in cold 0K medium. Time = 0 is the moment the Ca²⁺-loaded, ionophore-free RBCs were diluted into medium 90K at 37°C to activate Ca²⁺ extrusion by the PMCA. The pattern in panel A was observed in 7 of the 9 experiments of this series.