PDGFRB and neoplasm: We further analyzed FACS-sorted Pdgfrβ WT and Pdgfrβ KO p18−/−;Brca1MGKO tumor cells in dishes and observed that the population with characteristic morphological features of apoptosis (i.e., cell shrinkage, pyknosis, dense cytoplasm with tightly packed organelles) or dead cells was significantly increased in Pdgfrβ KO cells relative to that in Pdgfrβ WT cells after 5–7 days of culture (Fig. 4c).