Interpreting Microarray Data: Understanding the Ratios

Keeping in mind that each dot on the microarray corresponds to a gene, what do the numbers tell us?

When the ratio is greater than one, the gene was induced (stimulated to make more mRNA) by tumor formation. Gene A was induced fourfold.

When the ratio is less than one, the gene was repressed (to make less mRNA) by tumor formation. Gene C was repressed threefold.

Tumor formation did not affect Genes B and D.

Four circles of varying shades of green, red, and yellow arranged in a square and labeled A, B, C, and D.
Sample 1 light intensities and ratios of genes A, B, C, and D
Gene A Gene B Gene C Gene D
Red (tumor) 400 200 100 400
Green (normal) 100 200 300 400
Ratio Red/Green 4 1 0.33 1