Validation of SILAC data using Cln7 ko and wild-type MEFs. (A) Whole cell lysates (WCL) and lysosome-enriched fractions (LF) of Cln7 ko and wild-type MEFs were analysed by Cln5, Dpp7, cathepsin D (Ctsd) and cathepsin B (Ctsb) immunoblotting. α- and β-tubulin western blotting was performed to control equal loading. The positions of the molecular mass markers and the precursor, intermediate and mature forms of Cln5, Ctsb and Ctsd are indicated with white, grey and black arrowheads, respectively. (B) Specific enzymatic activities of β-hexosaminidase (Hex), β-galactosidase (Glb), β-glucuronidase (Gusb) and α-mannosidase (Man) in whole cell lysates of wild-type and Cln7 ko MEFs. The activities relative to wild-type controls are shown (mean ± SD, *P < 0.05, n = 4, two-tailed Student’s t-test). (C) Relative mRNA expression levels of selected lysosomal genes in Cln7 ko MEFs in comparison to wild-type controls (set as 1.0). Data are plotted as mean values ± SD (*P < 0.05, **P < 0.01, ***P < 0.001, n = 3–6, two-tailed Student’s t-test). n.d.: not detected.