By studying human non-small-cell lung cancer cell lines, HCI-H1299, A549, HCI-H1373, HCI-H460 and HCI-H1573, Lu et al. [59] showed the overexpression of PSMA-5, an α5 subunit of the 20S core proteasome involved with protein degradation. Here, PSMA5 is linked to non-small cell lung carcinoma.