EIF1AX is a core component of the eukaryotic 43S pre-initiation complex that facilitates translation initiation 1. It binds the mRNA cap-proximal region and promotes scanning of the 5'-untranslated region to locate the start codon 1. Together with EIF1 and EIF5B, EIF1AX coordinates assembly of the 48S pre-initiation complex and orients the initiator methionine-tRNA to enable 60S ribosomal subunit joining, forming the functional 80S initiation complex 2. EIF1AX is subsequently released after GTP hydrolysis by EIF5B 2. EIF1AX mutations are clinically significant in multiple human malignancies. Recurrent mutations occur in papillary thyroid carcinoma (PTC), poorly differentiated thyroid cancer (PDTC), and anaplastic thyroid cancer (ATC), where they are enriched in advanced disease 34. Notably, EIF1AX mutations display striking co-occurrence with RAS mutations in PDTC and low-grade serous ovarian carcinomas, cooperating to promote tumorigenesis 45. The prevalent C-terminal EIF1AX-A113splice variant stabilizes the pre-initiation complex and induces ATF4-mediated increases in protein synthesis while suppressing EIF2α phosphorylation, generating vulnerabilities to MEK, BRD4, and mTOR inhibitors 6. EIF1AX mutations also occur in uveal melanoma 78, establishing this translation factor as a recurrent oncogenic driver across cancer types.