Several of the results mentioned above suggest that secretion could be an efficient way to escape intracellular proteolysis. This hypothesis was particularly tested in E7 production [20] . E7 was indeed degraded when intracellular production was induced in late exponential or early stationary growth phase (Fig. 3) . E7 production was then tested in a clpP deficient strain (ClpP is reportedly the major house keeping protease in L. lactis; [37] ) and in a dnaK deficient strain (DnaK is an intracellular chaperone that may promote proteolysis by maintaining the protein in an unfolded state; [38] ). In exponential or stationary phase cultures, no significant difference in E7 patterns was observed between wild type and clpP - (Fig. 3 ) or dnaK -(not shown) strains: E7 was equally degraded in the cytoplasm and remained unchanged in supernatants samples. Altogether, these results indicate that E7 intracellular proteolysis is ClpP-and DnaK-independent. Until recently, only two cytoplasmic proteases, ClpP and FtsH [39] , have been identified in L. lactis. The existence of a third, as yet unidentified protease was postulated by studies of a clpP mutant suppressor [40] . E7 may thus be a useful screening target to identify a putative L. lactis protease that, as suggested by our data, is activated in stationary phase.