1. A method of preparing a plurality of cDNA libraries from single cells, comprising: obtaining a sample of cells; isolating a plurality of single cells from the sample within one or more channels of a microfluidic device such that single cells are fluidically isolated from each other; individually lysing at least some of the isolated single cells to liberate mRNA while keeping the mRNA from the single cells separate; reverse transcribing the mRNA liberated from the single cells isolated within the microfluidic device to form cDNA; and amplifying the cDNA, thereby obtaining the plurality of cDNA libraries from single cells.