To determine whether immortalized cells derived from the rat SCN (SCN 2.2) retain intrinsic rhythm-generating properties characteristic of the SCN, oscillatory properties of the SCN2.2 transcriptome were analyzed and compared to those found in the rat SCN in vivo using rat U34A Affymetrix GeneChips. SCN2.2 cells were expanded in 6-well plates. At 6-hour interval across 2 circadian cycles, cells from single 6-well plates were harvested and pooled for total RNA extraction. Keywords: other