Tumors have a lower interstitial pH compared to healthy tissues, with tumor acidity having emerged as a driver of tumor progression as it can lead to tumor immune evasion. Solute carrier family 4 member 4 (SLC4A4), which encodes a sodium bicarbonate cotransporter involved in pH regulation and homeostasis in normal tissue, was the focus of studies in pancreatic cancer resistance in in vivo preclinical models. Researchers tested the impact of Slc4a4 deletion in cancer cells on tumor growth, anticancer immunity and response to immunotherapy in murine models of pancreatic ductal adenocarcinoma (PDAC).