Heterogeneity analysis by SSP-RT-PCR in cdc unicellular erythroid cultures of CD34⁺Lin⁻ cells. At each culture round, 3 cells were processed separately for RT-PCR as described in Materials and Methods and 1 cell was transferred to the next culture round, and so forth. Note the absence of heterogeneity of individual cells from each culture round. An ethidium bromide-stained gel is shown.