Rac1, also known as RAS-related C3 botulinum toxin substrate 1, is an important member of Rho GTPases. It acts as a cytoskeleton regulation protein, participating in key processes such as cell adhesion, morphology, and movement [2]. Rac1 is involved in numerous signaling networks, like the regulation of actin cytoskeleton remodeling, activation of protein kinases (PAKs, MAPKs) and transcription factors (NF-κB, Wnt/β-catenin/TCF, STAT3, Snail), and production of reactive oxygen species [4].

Rac1 is highly expressed in various tumors, promoting processes like the tumor cell cycle, apoptosis, proliferation, invasion, migration, angiogenesis, and the regulation of tumor stem cells [2]. In bladder pathologies, its overexpression and dysregulation are common, contributing to tumorigenesis, tumor progression, epithelial-mesenchymal transition, and metastasis [1]. In metastatic cutaneous melanoma, Rac1 activation is related to cancer migration, invasion, angiogenesis, and metastasis, with the RAC1P29S driver mutation appearing in many cases [5]. Small molecule inhibitors targeting Rac1, such as NSC23766, EHT 1864, GYS32661, and MBQ-167, have shown potential in treating cancers, especially chemoresistant ones [1,3].

In conclusion, Rac1 is crucial for normal cellular functions and is significantly involved in disease conditions, particularly cancers. Its overexpression and dysregulation in various tumors make it an attractive therapeutic target. The development and study of Rac1 inhibitors offer promise for better management of these diseases, highlighting the importance of understanding Rac1's functions through in-vivo studies like gene knockout (KO) or conditional knockout (CKO) mouse models, though the references did not specifically detail findings from such models in this regard [1-5].

References:

1. Sauzeau, Vincent, Beignet, Julien, Bailly, Christian. 2022. Rac1 as a Target to Treat Dysfunctions and Cancer of the Bladder. In Biomedicines, 10, . doi:10.3390/biomedicines10061357. https://pubmed.ncbi.nlm.nih.gov/35740379/

2. Liang, Jiaxin, Oyang, Linda, Rao, Shan, Zhou, Yujuan, Liao, Qianjin. 2021. Rac1, A Potential Target for Tumor Therapy. In Frontiers in oncology, 11, 674426. doi:10.3389/fonc.2021.674426. https://pubmed.ncbi.nlm.nih.gov/34079763/

3. Bailly, Christian, Beignet, Julien, Loirand, Gervaise, Sauzeau, Vincent. 2022. Rac1 as a therapeutic anticancer target: Promises and limitations. In Biochemical pharmacology, 203, 115180. doi:10.1016/j.bcp.2022.115180. https://pubmed.ncbi.nlm.nih.gov/35853497/

4. Kotelevets, Larissa, Chastre, Eric. 2020. Rac1 Signaling: From Intestinal Homeostasis to Colorectal Cancer Metastasis. In Cancers, 12, . doi:10.3390/cancers12030665. https://pubmed.ncbi.nlm.nih.gov/32178475/

5. Colón-Bolea, Paula, García-Gómez, Rocío, Casar, Berta. 2021. RAC1 Activation as a Potential Therapeutic Option in Metastatic Cutaneous Melanoma. In Biomolecules, 11, . doi:10.3390/biom11111554. https://pubmed.ncbi.nlm.nih.gov/34827551/