RASA2 encodes a RAS GTPase-activating protein (RasGAP) that functions as an inhibitory regulator of RAS signaling pathways 1. The protein acts as a signaling checkpoint in T cells, where it is downregulated upon acute T cell receptor stimulation and increases with chr3 antigen exposure 1. RASA2 inactivates RAS by enhancing its intrinsic GTPase activity, thereby limiting MAPK pathway activation and controlling T cell activation and proliferation 2. The protein also interacts with G protein signaling, as mutant Gαi2 can sequester RASA2, leading to enhanced RAS activation and increased ERK/MAPK and PI3K-AKT signaling 3. Disease relevance includes associations with RASopathies, where RASA2 mutations contribute to developmental disorders 4, and copy number variants are linked to short stature disorders 5. Clinical significance is particularly evident in cancer immunotherapy, where RASA2 ablation enhances CAR-T cell function, increases antigen sensitivity, improves persistence, and prolongs survival in preclinical cancer models 16. RASA2 knockout also increases T cell interaction times with cancer cells and enhances killing efficacy 7. Additionally, RASA2 polymorphisms show interactions with body fatness in breast cancer risk 8.