**7. Conclusions**

Cell proliferation assays are widely used in molecular biology, tumor biology, pharmacology, and pharmacokinetics. It is important in studying not only the basic biological characteristics of cells but also a basic method for analyzing cell states and studying genetic traits. The increase of cell numbers can be simply measured by manual counting of cells under microscopy, using the dye exclusion method (i.e., trypan blue) to count only viable cells. Less fastidious, scalable methods include the use of cytometers; especially the flow cytometry allows combining cell counts ("events") with other specific parameters such as fluorescent probes for membranes, cytoplasm, or nuclei which allows distinguishing dead/viable cells, cell types, cell differentiation, and expression of a biomarker such as Ki67. Beside counting the increasing number of cells, cells can also be assessed based on the metabolic activity, such as the CFDA-SE or calcein-AM method measures not only the membrane functionality (dye retention) but also the functionality of cytoplasmic enzymes (esterases). Also, the MTT-type assays or the resazurin assay (fluorimetric) measures the mitochondrial redox potential. Most of these assays are endpoint assays and may or may not correlate well with the cell proliferation, depending on cell growth conditions, populations of different cells, drug interferences, or toxicity. For precise evaluation of druginduced proliferation rate changes, a continuous assay is highly desirable. Among various assay formats, the EZMTT dye showed initial promise in precise and sensitive detection of partial inhibition which is the cause of worldwide crisis in drug resistance, and the EZMTT method is expected to provide valuable information for exploring the pathogenesis of the disease, diagnosing the disease, and treating the disease.
