Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer-related deaths, characterized by highly invasion and metastasis. Aldo-keto reductase family 1 member C1 (AKR1C1) plays an important role in cancer cell proliferation and metastasis and has gained attention as an anticancer drug target. Here we report that the natural sesquiterpene lactone alantolactone (ALA) was shown to bind directly to AKR1C1 through the Proteome Integral Solubility Alteration (PISA) analysis, a label-free target identification approach based on thermal proteome profiling.