Fig. 4
From: Surface keratin 1, a tumor-selective peptide target in human triple-negative breast cancer
Human TNBC cells overexpress K1. (a) Mass analysis of cell lysate (MDA-MB-468) using MALDI-TOF mass spectrometry. The mass spectrum was obtained in positive linear mode and shows a mass peak for K1 (found 66819, expected ~ 67 kDa). Peak for housekeeping β-actin (~ 42 kDa) was also observed. (b) Coomassie stained gel showing resolved protein bands from lysates of normal (MCF-10A and MCF-12A) and TNBC (MDA-MB-231, MDA-MB-436, and MDA-MB-468) cells. (c) Identification of keratin 1 (K1) after in-gel trypsin digestion of the 67 kDa band for MDA-MB-468 cell lysate and LC MS/MS analysis of peptide fragments (in red). Thirteen peptide sequences matched K1 which corresponds to 22% protein sequence coverage. (d) Western blot analysis using anti-K1 antibody (LHK1 clone) of cell lysates (15 μg) shows overexpression of K1 (at 67 kDa) in TNBC cells versus no/minimal K1 expression in normal breast cells. β-actin was analyzed for all cell lysates (TNBC and normal breast) as a loading control.
