PDGFA and neoplasm: The significantly elevated expression of stromal cell-recruiting factors Pdgfa and Tgfb1 in tumor cells, as well as a strikingly high non-immune stromal cell/tumor cell ratio in naive and VPr tumors as compared with the regressing tumor (55 and 21 vs. 5, respectively; Fig. 3b, Extended Data Fig. 5c), indicate dynamic changes within the stromal compartment during treatment relapse.