KRT19 and cancer: Although correlations between α-SMA/CK-19 ratios and patient survival in PDOs were not supported by the PDAC FFPE TMA tested in our study, we believe that the disaggregation of tumors into single-cell suspensions, followed by their reaggregation in varying proportions of tumor cells and fibroblasts as PDOs in 3D culture, is vastly different from FFPE and represents a functional assay reflective of underlying cancer biology.