Figure 7

Principal component projection visualization. A projection of genes from a cell cycle data set into a 3D space defined by user selected Principal Components. Genes in each cluster are colored by phase (Red-G1, Green-S, Blue-G2, Yellow-M, and Cyan-M/G1). Cluster averages are displayed by larger solid spheres. The much larger transparent spheres show the region included by one standard deviation away from the average. (a) shows the top ten PCs of this data set and the percent of variance accounted for by each PC. (b) is a projection of cell cycle genes onto a space defined by the 1^st and 2^nd PCs. The separation is poor due to the first PC being highly correlated to noise in this data set. (c) shows the same data projected into a space defined by the 2^nd, 3^rd, and 4^th PCs. These PCs are highlighted in (a) corresponding to the axis colors in (c). Notice that the cell cycle phases are separated in order around the origin, and that G1 and M phase genes are opposite each other, which is consistent with their opposing expression profiles. (Data and clusters from [22]).