Figure 1. MCF10A cells are susceptible to perturbations in nuclear Zn²⁺.

(A) Background-corrected FRET ratios for MCF10A cells expressing NLS-ZapCV2 (top) and representative cells at each of the indicated time points (bottom). Addition of ZnCl₂ for 30 min results in an increase in labile Zn²⁺ from 24 ± 7.5 pM to 6.9 ± 2.9 nM. Addition of the Zn²⁺ chelator TPA at 58 min followed by the addition of Zn²⁺ and pyrithione at 75 min allows for calibration of the sensor and subsequent quantification of labile Zn²⁺. (B) Same as (A), but cells were treated with TPA at 20 min to deplete labile Zn²⁺. Each trace represents a single cell in the field of view. Lookup table values refer to the FRET ratio (background corrected FRET channel/background corrected CFP channel). Scale bar = 10 μm.