Ras

Ras proteins are small GTPases that function as molecular switches, cycling between inactive GDP-bound and active GTP-bound states to regulate intracellular signaling networks controlling cell proliferation, differentiation, migration, survival, and apoptosis^[1][2]. Mechanistically, activated Ras transduces signals from cell-surface receptors to major downstream pathways, including the RAF-MEK-ERK cascade, thereby coordinating growth-related transcriptional programs and cellular responses^[1][2]. The human RAS family comprises the highly homologous isoforms KRAS, NRAS, and HRAS, which share common effectors yet display distinct signaling outputs, partly due to sequence divergence within regions involved in allosteric communication and membrane interactions^[3][4]. Compared with related isoforms, KRAS exhibits unique membrane-targeting characteristics associated with its hypervariable region and is the predominant RAS isoform mutated in human malignancies, whereas NRAS and HRAS show different mutation frequencies and biological distributions across cancer types^[4][5][6]. RAS genes are among the most frequently mutated oncogenes in human cancer, and gain-of-function mutations commonly affecting codons 12, 13, and 61 promote persistent Ras activation that drives tumorigenesis in diverse experimental and clinical settings^[5][7]. For experimental applications, isoform-selective signaling mechanisms and Ras conformational regulation provide important frameworks for the development and evaluation of Ras-targeted inhibitors and mechanistic cancer models^[3][8].