Although the paradigm of cancer treatment has changed with the recent development of drugs targeting immune checkpoints (PD-1, PD-L1, etc.), there is still a need for new targets for anticancer drugs. To discover new potential targets for immunotherapy, we compared membrane protein expression in non-small cell lung cancer cells versus normal lung cancer cells and NSCLC cell lines with low and high PD-L1 expression using mass spectrometry. As a result, it was confirmed that membrane protein, which is one of the most highly expressed proteins in NSCLC cell lines, is highly expressed in normal cells and highly expressed in cells with low PD-L1 expression.