Table 1.

8-Br-cAMP-dependent secretion of PRPg2, PRPg2ΔS, and basic PRP^a

Clone expressing	Stimulated secretion of
	PRPg2	PRPg2ΔS	bPRPb
PRPg2	20 ± 2	NA	NA
PRPg2ΔS	NA	4.4 ± 0.4	NA
bPRP	NA	NA	10 ± 0
bPRP/PRPg2	15 ± 2	NA	12 ± 0

^a For each clone, duplicate wells of cells were labeled for 15 h with [³H]proline, chased first for 5 h and then for 2.5 h, and cells were harvested at the end of the experiment. During the second chase, 5 mM 8-Br-cAMP was added to one of the wells. Polypeptides were quantified by densitometry of fluorographs of immunoprecipitates from chases and cell lysates. The amount of each labeled polypeptide in each chase was normalized to the total labeled polypeptide (chases + cell extract). Stimulated secretion represents the difference between percentage of each polypeptide secreted in the presence and that secreted in the absence of 8-Br-cAMP. Data are expressed as mean ± range from two or three experiments each. 

^bbPRP, basic PRP; NA, not applicable.