Taken together, these data not only show the consistency of the immunofluorescence assay compared to a standard measure of cell viability, but they also suggest that assay conditions (feeder fibroblasts and TCM, -E, -I media) could be identified that do not alter the response of EGFR mutant or ALK-rearranged lung cancer cells to EGFR or ALK tyrosine kinase inhibitors (TKIs), respectively. The gene discussed is ALK; the disease is lung cancer.