MA-plot. MA-plot for differential expression analysis in four RNA-seq samples with two cell lines GM12878 and K562, annotated to illustrate the use of the grammar of graphics. Points is our geometric object, x axis indicates the normalized mean and the y axis indicates the log2 fold change. Aesthetics mapping took place between the groups and the color to use red to indicate the most significant differently expressed observation (gene). This plot uses Cartesian coordinates.
Yin et al. Genome Biology 2012 13:R77 doi:10.1186/gb-2012-13-8-r77