The drug action score reflects the degree of the drug action (promotion/inhibition) on cells (i.e. the degree of cellular response to drug perturbation), which is the Connectivity Score (CS) (Subramanian, A. et al. A next generation connectivity map: L1000 platform and the first 1,000,000 profiles. Cell 171, 1437–1452 (2017)) calculated between cell and drug based on genes up-regulated and down-regulated by drug perturbation. Two types of drug action score:
1. CS value: this is a continuous value (i.e. the Connectivity Score value) that represents the degree of drug action on cell.
2. Binary value: this score classified the drug action into three discrete categories:
Promotion: a score of 1 indicates that the drug has a significant promoting effect on cell;
Inhibition: a score of -1 signifies that the drug has a significant inhibitory effect on cell;
Neutral: a score of 0 suggests that the drug has no significant effect on cell.
Note: the significant promoting/inhibitory effect was determined by comparing the CS between drug and cell to a null distribution constructed based on random queries (random up- and down-regulated genes).