Chief cells, located primarily in the basal regions of the gastric glands, secrete which inactive proenzyme?

1. Chief cells are one of the four main secretory cell types in the gastric glands. 2. Located primarily in the basal regions of the glands, chief cells secrete pepsinogen, the inactive proenzyme form of pepsin. 3. HCl, produced separately by parietal cells, is necessary to convert this pepsinogen into active pepsin. 4. Gastrin is secreted by enteroendocrine G cells, while HCl and intrinsic factor are secreted by parietal cells, none of which is the specific proenzyme chief cells release. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 23 "The Digestive System", section 23.4, p. 1109_