While the genetic code carried in our DNA provides instructions for cells to manufacture specific proteins, it is a second code that determines which genes are in fact activated in particular cell types. (sciencedaily.com)
However, it is difficult to conclude from mixed tissue samples which genes are expressed by particular cell types. (ucsf.edu)
In each case there is interest in obtaining comprehensive, accurate data for particular cell types and in identifying patterns of variation within the data. (britannica.com)