RBM4 and esophageal squamous cell carcinoma: However, A549 lung adenocarcinomas cells, which are null for LKB1, were not prone to utilize glutamine whilst being reconstituted with RBM4 expression (Supplementary Fig. 6d), confirming the association between RBM4-LKB1 axis and glutamine utilization in ESCC cells as observed in above findings.