P21 and p27 expression in different subsets of single human hematopoietic cells.

Flow cytometry–sorted cells were individually selected by micromanipulator and analyzed using poly-dT–primed RT-PCR with radiolabeled gene-specific probes applied to the PCR product. Panels of 5 cells of each type were used to avoid individual cell artifacts or cell heterogeneity. The lower table states the ratios derived from quantitative analysis with densitometry software (NIHimager) of the tested genes normalized to GAPDH.