The baseline biopsies assessed for RA transport molecules in cancer and stromal cell compartments, demonstrated a differential distribution of fatty acid-binding protein 5 (FABP5) and cellular RA-binding protein 2 (CRABP2)26, using a well-validated method to distinguish stromal and epithelial compartments27, such that patients with increased stromal expression of FABP5 were more likely to achieve disease control (Fig. 4e–g, Supplementary Figs. 7 and 8, and Supplementary Table 11). Here, FABP5 is linked to cancer.