FN1 and neoplasm: PTHrP (−36 to −139) overexpression in tumor cells also significantly increases mRNA and cell surface expression of various integrins including α5, α6, β1, and β4. Though it has not been directly studied, PTHrP may push tumor cells out of dormancy by inducing integrin expression, cell adhesion to fibronectin, and activation of ERK signaling.