In 2020, Yang et al. [92] reported CTSK was significantly increased in A549 cells and dispersed in the cytoplasm, and the overexpression of CTSK promotes the proliferation, migration and invasion of A549 cells via the activation of mTOR, which can be blocked by CTSK knockout, suggesting that CTSK may promote the progression of NSCLC by activating the mTOR signaling pathway (Figure 5). Here, MTOR is linked to non-small cell lung carcinoma.