Adherent cell assay results affected by variable z-position mixing.

We demonstrate that modifying mixing dynamics after addition of organic solute into aqueous buffers dramatically affects cell morphology and protein expression. Variable z-position (VZP) or varying the height of aspiration and dispense positions during mixing eliminates artifactual effects. Here, we tested 4 adherent cell types and show effects of VZP on quantitative imaging, protein expression, viability, and morphology.