UniGene clusters re-aligned by Affymetrix using the Clustering and Alignment Tool (CAT: licensed from Double Twist formerly known as Pangea) and grouped into a more closely related set of sequences, called a sub-cluster, that best represent a single transcript (please note that any given gene may have different transcript variants and therefore two different sub-clusters may represent alternative forms of the same gene). All the members in an Affymetrix sub-cluster are aligned to derive the consensus sequence which is used for probe selection. Therefore, the sub-cluster members can be considered building blocks of the probe-sequence selection process. Please use the sub-cluster information in the NetAffx(tm) Analysis Center for an elaborate analysis of the probe set(s) of your interest.