PTHLH and neoplasm: Therefore, 1D11 does not directly influence tumor growth in vitro or in vivo, and these discrepancies with previous studies in anti‐tumor effects may be due differential regulation of factors implicated in tumor cell proliferation, including PTHrP,41 IL‐6,37 or Notch,67 that are controlled by TGFβ signaling, which may vary between tumor cell types and mouse strains.