We also observed a number of classes of perturbagens whose members tended to give multiple unique signatures. For example, 23 of 32 EGFR inhibitors were identified as having multiple signatures and 31 of 34 serotonin receptor antagonists gave multiple signatures, one extreme example being pindolol, whose signature in HCC515 was strongly dissimilar to its signature in other cell lines. These results suggest that the transcriptional response to perturbing these and other pathways may be context- and/or reagent-dependent.
