Immunofluorescence co‐staining experiments with POSTN, MYH11, and PDPN on parental and educated PS1 (see supplementary material, Figure S6G) revealed that while POSTN was diffusely expressed in PS1 across all the conditions, MIAPaCa‐2 and AsPC‐1‐educated PS1 showed a homogeneous decrease in POSTN (subtype A‐related) staining intensity and increase in MYH11‐positive (subtype B‐related) and PDPN‐positive (subtype C‐related) cells, with presence of double‐ and triple‐positive hybrid cells, suggesting for the first time (to our knowledge) an in vitro read‐out for cancer‐educated fibroblasts. The gene discussed is MYH11; the disease is cancer.