STK11 and esophageal squamous cell carcinoma: In addition, we also analyzed the data obtained from mass spectrometry-based proteomic profiling of ESCC tumors and adjacent non-tumor tissues,69 and found that RBM4 was increased, whereas LKB1 was decreased in ESCC samples (Supplementary Fig. 6a), further Spearman’s rank correlation analysis proved a significant and negative correlation between RBM4 and LKB1 (Fig. 7b).