ATF4 and KRT14 expression correlate with STIM1 levels in PDAC patients and PDXs. (A & B) Immunohistochemistry for STIM1, ATF4 and KRT14 in naïve patient tumor material (Pat) (B) and in the respective naïve PDX. (C) Quantification of STIM1, ATF4 and KRT14 staining in naïve patient samples, as well as in naïve PDXs and gemcitabine and gemcitabine and nab-paclitaxel co-treated PDXs. (D) STIM1, ATF4 and KRT14 staining in vehicle (Veh) as well as in gemcitabine (Gem) treated PDXs. (E) Immunohistochemistry for STIM1, ATF4 and KRT14 in vehicle (Veh) and gemcitabine and nab-paclitaxel (Gem/Pac) co-treated PDXs. (F) GSEA showing an enrichment for the UP-reversed genes in GöPDX13 co-treated with gemcitabine and nab-paclitaxel (Gem/Pac) compared to vehicle-treated GöPDX13. For all immunohistochemistry images: scale=20 μm (zoomed out) and 50 μm (zoomed in).