The response of wild-type and calreticulin knock-out murine embryonic fibroblasts (MEF) to melphalan exposure. (A) Wild-type and calreticulin knock-out MEF cells were seeded onto flat-bottom 2 mL wells at 105 cells per well in standard medium overnight and were then exposed to increasing doses of melphalan for 24 hours. Cells were then harvested with 0.1% trypsin and counted for viability with trypan blue staining. The results of 3 experiments are shown. The wild-type MEF cells (—●—) are significantly more sensitive to all doses of melphalan than the calreticulin knock-out cells (—○—; mean ± SD; P= .04, 2-tailed paired t test). (B) Lactate dehydrogenase release was directly measured to assess the cytotoxic effects of increasing doses of melphalan on wild type and calreticulin knock-out MEF cells. Triton-X 100–treated wells provided positive controls. The results of 3 experiments are shown. The wild-type MEF cells (—●—) are significantly more sensitive to all doses of melphalan than the calreticulin knock-out cells (—○—; mean ± SD; P = .006, 2-tailed paired t test).
