NTRK1 and Kaposi's sarcoma: Analysis of the molecular KS signature common to human KS tumors and our mouse KS-like tumors, showed consistent expression of KS markers VEGFR 1, 2, 3, Podoplanin with upregulation of angiogenesis ligands and receptors in vivo, pointing to the upregulation of various receptor tyrosine kinase signaling axes [3, 21].