Fig. 4. Expression of Cluster I genes in single-cell cDNAs and in the E14 brain. (A) Expression levels of Cluster I genes. Data from the probe sets that were expressed in Cluster I, but not in Cluster II/III, were used for clustering (n=175 probe sets; Welch's t-test, two-tailed, FDR<0.1 log fold-change cut-off <-2.5). Each column indicates one cell, and each row indicates one probe set on the microarray. The expression levels are color-coded from red (high) to black (low). Unlike the Cluster II/III genes (see Fig. 2), no particular pattern was seen in the Cluster I genes, except for the I⁺ II^- III^- IV⁺ genes (5730410E15Rik, Dab1). (B) Examples of in situ hybridization of the E14 mouse brain for Cluster I genes. In all cases, signals were seen in the VZ. The 5730410E15Rik and Dab1 genes were expressed in both the VZ and CP (n,o), consistent with the single-cell gene expression profiles (A). GenePaint set IDs are indicated at the bottom right of some panels.