Table 1.

Genotoxic stress-induced responses that contribute to reduction in colorimetric/fluorometric measurements in multiwell plate assays in proliferating versus non-proliferating cultures.

Assay	Proliferative Status	Responses Contributing to IC50 Values
Tetrazolium-Based Resazurin-Based (e.g., MTT, MTS, XTT, WST-1, WST-8, CellTitre-Glo)	Proliferating cultures (≥24 h treatment)	-Decrease in metabolic activity of individual cells -Checkpoint activation (proliferation arrest) -Reversible apoptosis (proliferation arrest) -Onset of senescence (proliferation arrest) -Polyploidy/multinucleation (proliferation arrest) -Loss of cell viability (death)
	Non-proliferating cultures	-Decrease in metabolic activity of individual cells -Loss of cell viability (death)
Crystal Violet Staining	Proliferating cultures (≥24 h treatment)	-Checkpoint activation (proliferation arrest) -Reversible apoptosis (proliferation arrest) -Onset of senescence (proliferation arrest) -Polyploidy/multinucleation (proliferation arrest) -Loss of cell viability (death)
	Non-proliferating cultures	-Loss of cell viability (death)