Comparison of the sulforhodamine B protein and tetrazolium (MTT) assays for in vitro chemosensitivity testing.

The sulforhodamine B (SRB) protein stain assay was compared with the tetrazolium (MTT) colorimetric assay for in vitro chemosensitivity testing of various human tumour cell lines. The SRB assay provided a better linearity with cell number and a higher sensitivity, and its staining was not cell-line dependent. In contrast to the MTT assay, the SRB assay stained recently lysed cells. Cell debris, however, was not stained by SRB and therefore the drug sensitivity data were not affected.