Fig. 4
β-Actin quantification from NIH 3T3 extracts. Aspiration and quantification of β-actin from the cytoplasm of a single NIH 3T3 cell. Fluorescence from the spot was used to extrapolate the number of molecules from the standard curve shown in Fig. 3. The total number of molecules in the 20–50 fL extract was calculated to be 6.5 ± 2.5 × 105 (mean ± range, N = 4), which scales to 6.5 ± 2.5 × 107 for a total cell volume of ~ 2000 fL