PF4 and histiocytoma: CXCL4/PF-4 was found to be significantly decreased in patients suffering from pancreatic cancer [38], in sera of metastatic prostate cancer patients compared to healthy persons or non-metastatic prostate cancer patients [42] and in metastatic cancer patients (colorectal cancer, renal cell cancer, malignant fibrous histiocytoma, leiomyosarcoma, peripheral neuroectodermal tumor) compared to controls [43].