PTH and neoplasm: While both PTH immunoreactivity and PTH mRNA levels frequently exhibitedheterogeneous staining patterns in the tumor tissue, they too did not correlate in terms ofspatial distribution within individual tumors (Fig. 2).Tumor cell areas with oxyphilic cell differentiation generally exhibited lower PTHimmunoreactivity and PTH mRNA levels as compared with adjacent chief cells.However, there was no significant difference between tumors with dominant oxyphilic and chiefcell differentiation (data not shown).