Guide to CellMontage
What is CellMontage?
CellMontage is a system for searching gene expression databases for cells or tissues similar to the query gene expression profile. The similarity of two profiles is computed by comparing the order of genes ranked by expression. Although this is a simple measure we have observed that it is sufficient to characterize cell types across different microarray platforms.
What characterizes cells?
Gene sets and expression value ranges differ between platforms, making direct comparison impossible. Given this situation, we use "gene expression ranks" as a way to compare expression data across platforms.
How many genes are needed to detect cell types?
We investigated the top hits obtained by searches using queries from seven normal cell types. The precentage of top hits from each cell type increased rapidly as the number of genes used in the query increased. The number of randomly chosen genes required to retrieve seven normal cell types is only 64-128 (on the same platform).