<prompt> A 88 year-old woman from Mexico is admitted to the hospital following a bout of severe vomiting and generalized weakness. Initial laboratory values reveal elevated Cat levels. The referring physician tells you that she has breast cancer and her bone scan indicates metastasis to bone. The most likely cause of hypercalcemia is:Increased PTH productionIncreased responsiveness of the PTH receptor 1Increased PTHrP productionDecreased responsiveness to calcitonin  <response>: Increased PTHrP productions 