In the present study, we tried to investigate whether protein kinase C (PKC) activator, phorbol 12-Myristate 13-Acetate (PMA), and PKC inhibitors, $G"{o}-6976$, Ro-31-8220 and rottlerin significantly affect basal mucin relesed from cultured airway goblet cells. Confluent primary hamster tracheal surface epithelial (HTSE) cells were metabolically radiolabeled with $^3H$-glucosamine for 24 hr and chased for 30 min in the presence of each agent to assess the effects on $^3H$-mucin release. The results were as follows: (1) PMA increased mucin release from cultured HTSE cells, during 30 min of treatment period; (2) However, $G"{o}-6976$, Ro-31-8220 and rottlerin did not significantly affect mucin release, during 30 min of treatment period. This finding suggests, at least in part, that PKC might playa minor role in the signaling pathways involved in basal - physiological or constitutive - mucin release from airway goblet cells, although further studies are needed.