ENCODE Tier 1, Tier 2 and Tier 3 Cells

Excerpts from "ENCODE Cell Types 2007 - 2012"

"Tier1 cells are of higher priority, and should be used within experiments before Tier2 cells. Additional cell types beyond the designated Tier1 and Tier2 could be used for ENCODE production; these are selected at the discretion of individual data production groups, and are designated Tier3."

===============================================
Excerpts from "ENCODE Project Common Cell Types"

"These common cell types include both cell lines and primary cell types, and plans are being made to explore the use of primary tissues and embryonic stem (ES) cells.

Cell types were selected largely for practical reasons, including their wide availability, the ability to grow them easily, and their capacity to produce sufficient numbers of cells for use in all technologies being used by ENCODE investigators. Secondary considerations were the diversity in tissue source of the cells, germ layer lineage representation, the availability of existing data generated using the cell type, and coordination with other ongoing projects. Effort was also made to select at least some cell types that have a relatively normal karyotype."

Detailed descriptions of tier 1 and 2 cells were included in the link above.