Traditional
qPCR approaches adapted for use in single cells show
that, even in homogeneous cell lines using a ΔΔCT calculation to interpret qPCR data, intercellular
variability can be observed. The fold difference in expression of
BCR-ABL for each cell population was compared to the average BCR-ABL
expression of the extracted RNA. For K562 cells, the use of ABL as
a control gene and comparison of its expression to BCR-ABL gene expression
is a typical approach. As the input cell number decreases, the mean
expression value, indicated by a horizontal red line in each group,
remains the same as that of extracted control RNA, but the intercellular
variability becomes more apparent.