*4.8. Western Blot*

Cells were lysed in RIPA (Radioimmunoprecipitation assay) buffer containing proteaseinhibitor cocktail (dilution 1:1000) 2, 6, or 24 h after UVB irradiation. Lysates were centrifuged at 15,000 rpm for 5 min at 4 ◦C. Protein concentration in the supernatants was measured using a Pierce BCA (Bicinchoninic acid) assay kit (Thermo Fisher Scientific, Waltham, MA, USA). Protein samples were mixed with 5× loading buffer (bromophenol blue (0.25%), β-mercaptoethanol (5%; Sigma-Aldrich, St. Louis, MO, USA), glycerol (50%; Sigma-Aldrich, St. Louis, MO, USA), SDS (sodium dodecyl sulfate; 10%; Duchefa Biochemie, Haarlem, The Neatherlands), Tris-HCl (0.25 M, pH 6.8; Sigma-Aldrich, St. Louis, MO, USA)), then boiled at 100 ◦C for 10 min. Proteins were separated on 7.5%, 10%, or 12.5% polyacrylamide gels, then transferred to nitrocellulose membranes (Bio-Rad, Hercules, CA, USA). Membranes were washed in TBS-T (TBS buffer containing 0.05% Tween-20), blocked in 5% nonfat dry milk for 1 h, and incubated with the primary antibody overnight at 4 ◦C. Antibodies used for Western blotting are listed in Supplementary Table S1. Antibodies were diluted in TBS-T containing 5% BSA. After washing with TBS-T, membranes were incubated with horseradish peroxidase (HRP)–conjugated goat anti-mouse/anti-rabbit IgG secondary antibodies (Bio-Rad, Hercules, CA, USA; dilution 1:2000) for 1 h with gentle shaking. After washing, protein bands were visualized using Pierce™ ECL Western

Blotting Substrate (Thermo Fisher Scientific, Waltham, MA, USA) or SuperSignal West Femto Maximum Sensitivity Substrate (Thermo Fisher Scientific, Waltham, MA, USA). For band quantification, ImageJ 1.8.0 software (Research Services Branch, National Institute of Mental Health, Bethesda, MD, USA) was used.

### *4.9. Statistical Analysis*

The normality of the population was determined using the Shapiro–Wilk test. If two groups were compared, we used independent t-test (two tailed), as the Shapiro–Wilk test showed normal distribution. When we compared three or more groups, one-way ANOVA complemented by Dunnett's post-hoc test was used, if the data showed normal distribution. Kruskal–Wallis test complemented with Dunn's post hoc test was performed, if the distribution of the data was not normal. Statistical calculations were performed using GraphPad Prism 7 (GraphPad Software Inc., San Diego, CA, USA) and SPSS 25 software. (SPSS package for Windows, Release 25.; SPSS, Chicago, IL, USA). Data are presented as mean ± SEM. Statistically significant differences are denoted by \*, \*\*, and \*\*\* for *p* < 0.05, *p* < 0.01, and *p* < 0.001.

**Supplementary Materials:** Supplementary Materials can be found at https://www.mdpi.com/1422 -0067/22/4/1638/s1.

**Author Contributions:** Conceptualization: É.R., E.F., and G.P.; methodology: E.F. and C.H.; formal analysis: E.A.J.; writing—original draft preparation: E.F.; writing, reviewing, and editing: C.H., É.R., G.E., and G.P.; funding acquisition: É.R.; supervision: É.R. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the European Union and the European Regional Development Fund GINOP-2.3.2-15-2016-00005; the Hungarian National Research Development and Innovation Fund NKFIH K120206; and the ÚNKP-20-4-I New National Excellence Program of the Ministry for Innovation and Technology from the source of the National Research, Development, and Innovation Fund.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest. G.P. is a consultant for ADC Therapeutics and Buffalo Biolabs.

#### **Abbreviations**

