CD44 and esophageal adenocarcinoma: In an in vitro model of starvation with depletion of glucose and serum factors in the esophageal adenocarcinoma cell line SKGT-4, the starvation-responsive increase in expression levels of HSP90 (and HSP70) was associated with the expression of CSC markers, such as CD44, ALDH1A1, and ABCG2 [78].