Keratin 16

Protein was extracted using cell lysis buffer (Cell Signaling Technology, Beverly, MA, USA). Protein content in the lysate was determined using the BCA Protein Assay (Pierce, Rockford, IL, USA). Equal amounts of protein were run on 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels and then transferred to a polyvinylidene difluoride membrane. The following antibodies were used: matrix metalloproteinase (MMP)-1, SREBP-1, and Keratin 16 (Santa Cruz Biotechnology, Santa Cruz, CA, USA), nuclear factor kappa B (NF-kB) p65, interleukin (IL)-1α, IL-8, IL-6, collagen1, adiponectin, and phosphorylated insulin- like growth factor 1 receptor (Abcam, Cambridge, MA, USA), phospho ERK, Akt, and PI3K (Cell Signaling Technology), MMP-7, and MMP-12 (Thermo, Pittsburgh, PA, USA). Secondary anti-rabbit immunoglobulin G (IgG) and anti-mouse IgG antibody (Cell Signaling Technology) were used to detect primary antibodies. Films of blots were analyzed and quantified using a densitometric program (TINA, Raytest Isotopenmebgerate, Straubenhardt, Germany). All experiments were repeated a minimum of four times.