Wilcox v. St. Mary's University, 531 S.W.2d 589, 592-93 (Tex. 1975). Although a motion for summary judgment does not shift the burden of proof imposed by the parties' pleadings, Cloyd v. Champion Home Builders Co., 615 S.W.2d 269, 271 (Tex.Civ.App. — Dallas 1981, writ ref'd n.r.e.), every reasonable inference is indulged in favor of the non-movant. Therefore, we must determine whether Republic established its right to recover as a matter of law.
Wilcox v. St. Mary's University, 531 S.W.2d 589, 592-93 (Tex. 1975). Although a motion for summary judgment does not shift the burden of proof imposed by the parties' own pleadings, Cloyd v. Champion Home Builders Co., 615 S.W.2d 269, 271 (Tex.Civ.App.-Dallas 1981, writ ref'd n.r.e.), every reasonable inference is indulged in favor of the non-movant. Accepting Mostek's allegations as true, Chemetron had the option of conclusively showing: 1) that a fact required to establish at least one element necessary to each of Mostek's causes of action did not exist, American Petrofina, 597 S.W.2d at 470; or, 2) conclusively showing that notwithstanding Mostek's ability to prove its claims, Chemetron was insulated from liability by some defense.