(a) Structure of the wildtype USP15 construct with the V5 protein tag, and the respective catalytic mutant USP15C298S. (b) Protein expression by Western blot using an anti-V5 AB, loading control tubulin for the selected clones from LN-229 and LN-428 with stable expression of USP15, or USP15C298S (USPC/S), or empty vector controls. (c) Growth of USP15, or USP15C298S (USPC/S) overexpressing clones, and respective empty vector control (pIRES2/EGFP) followed over 5 days in culture. The error bars indicate standard deviations of triplicate samples. (d) Adhesion-independent growth in soft agar, representative images, and quantification of total colony numbers. Empty vector control, eV, black; USP15, blue; USP15C/S, green. Histogram shows data as mean +/-SD.