Tracking KLK6 expression across the histopathological continuum of lung adenocarcinoma development—from pre-invasive in situ adenocarcinoma (AIS) to minimally invasive adenocarcinoma (MIA) and finally to invasive adenocarcinoma (IAC) by spatial transcriptomics—revealed a gradual increase in KLK6 expression that paralleled the advancement of malignant progression (Figure 11E), underscoring its potential role in driving tumor invasion and aggressiveness. Here, KLK6 is linked to adenocarcinoma in situ.