ERBB2 and neoplasm: Concerning the role of PDGFRβ signaling in pericytes and stromal fibroblasts and their relationship with biological parameters and survival, in 512 early BC specimens it has been found that around 35% of tumors are strongly positive for PDGFRβ expression and that this is related with high tumor grade, ER and PR negativity, HER2 expression, proliferation rate, and tumor size [54].