EIF1AX is a core component of the eukaryotic translation initiation machinery, functioning within the 43S pre-initiation complex to facilitate mRNA scanning and start codon recognition. The protein enhances cap-proximal complex formation and, together with EIF5B, orients the initiator methionine-tRNA to enable 60S ribosomal subunit joining and formation of the functional 80S initiation complex. Its globular domain occupies the A site of the 40S ribosomal subunit, and it is released after 80S complex assembly. EIF1AX mutations are clinically significant in thyroid cancers, where they are markedly enriched in poorly differentiated and anaplastic thyroid cancers and show striking co-occurrence with RAS mutations 1. The C-terminal EIF1AX-A113splice variant, the most prevalent mutation in advanced thyroid cancer, stabilizes the pre-initiation complex and induces ATF4, a stress sensor that suppresses EIF2α phosphorylation and increases global protein synthesis 2. This mutation cooperates with RAS to drive tumorigenesis and generates therapeutic vulnerabilities to MEK, BRD4, and mTOR kinase inhibitors 2. EIF1AX mutations also occur recurrently in papillary thyroid carcinoma as an independent driver 3, uveal melanoma 4, and low-grade serous ovarian carcinomas, where they co-occur with NRAS mutations to promote proliferation 5. In endometrial carcinoma, cytoplasmic EIF1AX relocation correlates with advanced disease and poor recurrence-free survival, and targeting its nucleocytoplasmic transport may offer therapeutic benefit 6.