EGF and breast cancer: We found that in all breast cancer cell lines analyzed, IP3-sponge-NLS nearly abolished nuclear Ca2+ signals induced by EGF (4T1: control = 707 ± 73%; IP3-sponge-NLS = 179 ± 13%; MDA-MB-231: control = 179 ± 3.5%; IP3-sponge-NLS = 105 ± 1.5%; MDA-MB-468: control = 248 ± 12%; IP3-sponge-NLS = 94 ± 2%; n = 55 cells for each condition), (Fig 1C, 1E and 1G).