ARHGEF39 and lung adenocarcinoma: Within receptor tyrosine kinase (RTK) networks, Rac–GEFs such as FARP1, ARHGEF39, and TIAM2 (activated by EGFR/c‐MET in lung adenocarcinoma) activate Rac1 via PI3K to regulate distinct aspects of membrane ruffling dynamics (FARP1 and ARHGEF39 maintain ruffles stability, while TIAM2 participates in their formation) [134, 135].