Fig 1: Validation of elevated levels of resident lysosomal proteins in whole-cell extracts. (a) Immunoblot of ARSA (arylsulfatase A) in total cell homogenates from control or palbociclib-treated (palbo) SK-MEL-103, treated or not with ammonium chloride and leupeptin (N/L) 16 h before cell lysis, as indicated. Quantification of three biological independent replicates (n = 3) (top) and representative immunoblot (bottom). ***p < 0.001, **p < 0.01, *p < 0.05, 2-way ANOVA test. (b) Immunoblot of NAGLU (N-acetyl-alpha-glucosaminidase), same as in panel (a). (c) Immunoblot of EPDR1 (ependymin related 1), same as in panel (a). (d) Immunoblot of CTSF (cathepsin F), same as in panel (a). (e) Immunoblot of HLA-DMB (beta subunit of MHC-II DM), same as in panel (a). (f) Immunoblot of IMR90-ER:RAS from control and senescent cells. Senescence was induced by irradiation (20 Gy, 2 weeks) or by addition of tamoxifen (1 µM, 3 weeks).