CD49f⁺ cells have higher level of tonic signaling than MPPs. (A) Levels of each signaling intermediate are shown for the unstimulated cells in the CD33⁺ and CD33⁻ subsets of the CD49f⁺ compartment and in the MPP compartment. Median values are shown as black lines. Histogram colors indicate the relative difference from the MPP compartment. (B) Median levels of phospho-STAT5, AKT, S6, and ERK1/2 over time corrected for the unstimulated values are shown as lines for the CD33⁺ subset (green) and the MPPs (black). Shaded areas indicate the interquartile ranges. Points are placed at each time. Bootstrapped probabilities are indicated as follows: ^•P = .1; *P = .05; **P = .01; ***P ≤ .001.