In humans, the mucin-5B protein is primarily found in whole saliva and in normal lung and cervical mucus, with Hsa-mucin-5B abundance demonstrated to be altered in respiratory conditions such as chronic rhinosinusitis (chronic sinusitis) and chronic obstructive pulmonary disease (COPD) and in gastric diseases that result from Helicobacter pylori infection [56,57]. Here, MUC5B is linked to chronic obstructive pulmonary disease.