2.1. Cell lines and pleural fluids

HOMC‐D4 cell lines established in our laboratory ³⁵ were used for assays at passages 10–20. They were deposited and are now available from RIKEN BioResource Center. NCI‐H2052 and NCI‐H2373 cells were purchased from the American Type Culture Collection. All cell lines were cultured in RPMI‐1640 medium supplemented with 10% (v/v) fetal bovine serum (FBS) and 1% (v/v) antimicrobials at 37°C in a humidified incubator with 5% CO₂. Pleural fluid samples from patients were collected and centrifuged at 3000 rpm for 10 min, and the supernatant was stored at −80°C until use. The research protocol was approved by the Ethics Committee of Aichi Cancer Center Research Institute.