For in vivo immunofluorescence assay, mouse skins separated from back were embedded with OCT solution (Leica Biosystems Richmond Inc.,) in frozen section. Frozen section was cut into 6‐μm‐thick sections under a microscope (Cryostat CM1850, Leica Biosystems,) and then attached to microscope slides (Thermo Fisher Scientific,).
Cells and frozen tissues were fixed with 4% formaldehyde and permeabilized with ice‐cold 100% methanol. After blocking, cells were incubated with specific antibodies at 4°C overnight. Goat anti‐rabbit IgG H&L conjugated to Alexa Fluora® 488 secondary antibodies (Abcam) were incubated with the cells for 1–2 h. Nuclei were counterstained with DAPI antibody (VECTASHIELD®: Vector Laboratories, Burlingame, CA). The location of c‐Jun was determined using a confocal laser scanning microscope (Carl Zeiss Co Ltd.,).