Primary myelofibrosis (PMF) is a proliferative disease of the bone marrow which is characterized by the presence of somatic, acquired mutation in hematopoietic stem cells, a resulting proliferation of cells of the megakaryocytic lineage and, as the primary disease manifestation, progressive bone marrow fibrosis. The mechanisms leading to myelofibrosis are largely unknown, however, prevailing evidence suggests a decisive role of platelet-derived growth factors (PDGFs) and their cognate receptors. Using the Gata-1low mouse model for PMF, this study aimed at characterizing expression, activation and regulation of PDGF receptor β (PDGFRβ) in different stages of the disease. RNAsequencing, qPCR, protein expression analyses, multiplexed immunohistochemistry and, as a novel approach in bone marrow tissue, an in situ proximity ligation assay (PLA) was applied to provide a detailed characterization of PDGFRβ signaling and regulation during development of myelofibrosis. Therefore, murine bone marrow was analyzed the at a pre-, an early, and an overt fibrotic stage. An increase in gene and protein expression of the PDGF signaling components in early and overt fibrotic bone marrow, and a cell-type-specific expression of the ligands and the receptors was detected. PDGFRα expression was predominantly seen in megakaryocytes, whereas PDGFRβ was expressed in fibroblast, underlining the important role of PDGFRβ in fibroblast proliferation within disease development. PDGFRβ and PDGF-B protein expression was enhanced in overt fibrotic bone marrow, along with an increase in PDGFRβ–PDGF-B interaction, analyzed by PLA. However, PDGFRβ tyrosine phosphorylation levels were not elevated. Hence, further analyses focused on regulation of PDGFRβ by protein tyrosine phosphatases (PTPs) as endogenous PDGFRβ antagonists. Gene expression analyses showed distinct expression dynamics among PDGFRβ-targeting PTPs. In particular, enhanced T-cell PTP (TC-PTP) protein expression and PDGFRβ–TC-PTP interaction was observed in early and overt fibrotic bone marrow of Gata-1low mice. In vitro, TC-PTP (Ptpn2) knockdown increased PDGFRβ phosphorylation at Y751 and Y1021, leading to enhanced downstream AKT and phospholipase C γ1 (PLCγ1) activation in fibroblasts. Further, Ptpn2 knockdown cells showed increased growth rates when exposed to low-serum growth medium. Taken together, this study provides detailed insights into PDGF signaling during PMF development and suggests PTPs as novel, and so far unrecognized components in PMF.