Fluorescent Protein-Assisted Purification for Gene Expression Profiling

Cell type-specific expression of fluorescent proteins allows the purification of rare cells from complex ­tissues by flow cytometry. This strategy is especially useful for molecular analysis of cancer cells because these cells can be effectively purified away from the noncancerous tumor stroma. Coexpression of bioluminescence with fluorescence makes further allows in vivo tracking of cancer cells, which can then be purified at specific tumorigenic stages. Here, we describe protocols for purifying rare skin stem cells, and for in vivo monitoring and purification of cancer cells from lung metastases. Also described is a protocol for the isolation of total RNA from the purified cells for the purpose of performing gene expression profiling.