FIG. 1.

Illustration of limiting dilution methodology to calculate precursor frequency. (A) Cells are plated after serial dilution (cell dose), and are subjected to a stimulus, that is, differentiation medium. The response at each dosage is quantified and the number of responding wells is determined. (B) The number of nonresponding wells at each dilution is plotted on a semi-log plot as a function of cell dose, and points are best fit to a trend line. Using the exponential form of the equation, the precursor frequency (x) can be calculated assuming y=0.37.