Fig. 6

Erk blocks ∆Np63α-dependent signals that upregulate Irf6 in detached ErbB2-overproducing breast epithelial cells. a, b MCF10A and MCF-ErbB2 cells (a) or MCF10A and MCF-MekDD cells (b) were cultured detached from the extracellular matrix (3D culture) for 3 h and assayed for ΔNp63 levels by Western blotting. c–e MCF-ErbB2 cells transfected with 100 nM control RNA (cRNA) or p63-specific small interfering RNA (p63siRNA) 14 or 15 were kept in 3D culture for 24 h in the presence of dimethyl sulfoxide or 1 μM SCH772984 and assayed for ΔNp63 (c), Irf6 (d), or phospho-Rsk (pRsk) and Rsk (e) expression by Western blotting. f MCF-ErbB2 cells were infected with the control or the ΔNp63α-encoding Moloney murine leukemia virus, kept in 3D culture for 3 h along with MCF10A cells, and assayed for ΔNp63 levels by Western blotting. β-actin was used as a loading control in (a–f). g, h Schematic representation of events that take place in detached nonmalignant (g) and ErbB2-overproducing (h) breast epithelial cells. g Detachment-induced signals can upregulate Irf6 in the nonmalignant cells only in the presence of ΔNp63α. h ErbB2 blocks both the indicated detachment-induced signals and ΔNp63α expression in detached breast cancer cells. In the absence of the indicated detachment-induced signals, Irf6 is not upregulated in ErbB2-overproducing cells