PLR for cell mechanotyping by q-DC. (A) Creep trajectory for a single, representative HL-60 cell (gray dots). Lines represent the least-squares fits of viscoelastic models to the creep data: Maxwell (red dotted line), Kelvin-Voigt (KV, purple long-dashed line), SLS (blue dot-dashed line), and PLR (green short-dashed line). (B) Residuals for the least-squares fits of the viscoelastic models to the creep trajectories of a population of HL-60 cells (N = 550), as shown in Fig. 1E. Shown here are the bootstrapped median residuals; error bars represent the bootstrapped confidence interval. ∗p < 0.05, ∗∗∗p 0.001. (C and D) Heat maps show (C) the apparent elastic modulus, Ea, and (D) the fluidity, β, of HL-60 cells as a function of transit time, TT, and cell diameter, Dcell, which is measured in the microfluidic channel before the cell enters the constriction. Each bin represents the median Ea or β of N = 3–47 single cells.