KRT19 and cancer: Immunofluorescence staining of the KPC-murine tumor-derived organoids confirmed the formation of PDAC organoids, as shown by the expression of two biomarkers, SRY-Box Transcription Factor 9 (SOX9) [38], a lineage marker for pancreatic formation (Fig. 1b, upper panel), and cytokeratin 19 (CK19) [39, 40], a biomarker for epithelial cancer cells (Fig. 1b, lower panel).