Parathyroid hormone-related protein (PTHrP) is endoproteolytically processed to yield a
family of mature secretory forms. These include an amino-terminal, a mid-region, and a
carboxyl-terminal form. Prior studies suggested that the mid-region form is secreted via the
regulated secretory pathway, whereas the amino-and carboxyl-terminal forms are secreted
via the constitutive pathway. Further, PTHrP is unusual in that it is produced under normal
circumstances by neuroendocrine cell types as well as by prototypical constitutively …