Fig. 5. Expression of marker and signaling pathway genes in single-cell cDNAs, and cell-to-cell variation in the expression of determinants. (A) Expression of marker and signaling pathway genes. 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). All Cluster I cells expressed some neuronal differentiation-related genes at various degrees. Neurog2 and Dll1 are marked with asterisks. Cells strongly expressing Dll1 were mostly Cluster II cells. Hes3, Dll4 and Jag2 showed low signal levels and are not included in this figure. (B-E) Cell-to-cell variations in gene expression in the Cluster I population. Scatter diagram of the Hes1 and Fgfr3 (B), Neurog2 (C), Dll1 (D) or Neurod2 (E) expression levels from cDNAs of 70 single cells. Each symbol indicates one cell, and axes are on a natural logarithmic scale.