The data come from a National Cancer Institute study of gene expression in cell lines drawn from various sorts of cancer. Each row corresponds to a different cell line. The type of cancer is identified by the first two or three letters of the row names, e.g. CO is colon, ME is melanoma, RE is kidney.
A data frame
NCI60_snippet with 60 rows and 6000 variables.
For each row, there are 6000 measurements of the gene expression as identified by activity on a microarray probe. The variable names are the names of the probes.