USP7 and non-small cell lung carcinoma: On the other hand, after co‐expressing ubiquitin plasmids with specific mutations, the subsequent IP/IB assays showed that USP7 specifically prevented c‐Abl from K48‐linked polyubiquitination (Figure 4D), and this result was further confirmed in NSCLC cells by overexpressing or knocking out USP7 (Figure 4E).