Fig. 1.

Overview of ACTION. ACTION consists of five main steps: i A biologically inspired metric to capture similarity among cells. ii A geometric approach for identifying the set of primary functions. iii An automated mechanism for identifying the number of primary functions needed to represent all cells. iv An orthogonalization procedure for identifying key markers for each primary function. v A statistical approach for identifying key regulatory elements in the transcriptional regulatory network. These steps are grouped into three main components in the ACTION method that are each discussed in the methods section