Proteomic analysis identifies SERPINB5 as an interacting partner of DSP in keratinocytes. (a) Volcano plot showing differential protein expression in sgDPM1 with respect to control sgNT1 HaCaT keratinocytes from three biological replicates. −Log 10 P values above 1.3 (0.05) were considered significant (marked by gray line on plot). Orange dots indicate proteins which were significantly downregulated in DPM1 KD cells, whereas blue dots indicate proteins that were significantly upregulated in DPM1 KD cells. (b) STRING-based biological pathway analysis of significantly modulated proteins (orange: downregulated pathways and blue: upregulated pathways). X-axis denotes −log10 of FDR values, with a cutoff set to 0.05 for significance. (c) Heat map showing binding partners of DSP that were absent in either sgNT1 or sgDPM1 cells in at least two biological replicates (N = 3). (d and e) PLA assay showing SERPINB5 and DSP interaction as white dots. Nucleus stained with DAPI. Scale bar: 10 µm distance. Each dot represents individual biological replicates. Unpaired Student’s t test. (f) Co-immunoprecipitation assay showing DSP binding to SERPINB5-GFP expressed in HaCaT sgNT1 cells. Expression of GFP served as negative control. (g) Immunostaining of EGFR in sgNT1 and sgDPM1 HaCaT keratinocytes. White dashed boxes indicate areas zoomed in below. Scale bar: 10 µm distance. (h and i) Western blot and respective quantification of phosphorylated EGFR at Y1068 in sgNT1 and sgDPM1 HaCaT keratinocytes. Each dot represents individual biological replicates. Unpaired Student’s t test. (j and k) Co-immunoprecipitation assay showing DSP binding to SERPINB5-GFP expressed in HaCaT sgNT1 cells treated with DMSO and erlotinib, respectively. Quantitation of DSP co-immunoprecipitated signal intensity normalized to respective immunoprecipitated GFP intensity. Each dot represents individual biological replicates. Unpaired Student’s t test. Source data are available for this figure: SourceData F3.