Secretion of effector proteins SopB and SipB via SPI-1 T3SS was impaired in ∆crp. Wild type (WT), CP327 or PQ518 strains transformed with pUC19 (v1), pUC19 encoding sopB-myc (SopB), sipB-myc (SipB), p705 M (v2) or p705 M encoding crp-myc (CRP) were grown under conditions that induced SPI-1 T3SS function. Bacterial culture supernatants (sup.) and pellets (bac.) were harvested, normalized and subjected to Western blot analysis with an antibody to Myc-tag. The results of the SopB secretion assay in WT, CP327 and PQ518 strains (A), SipB secretion assay in WT and CP327 (B) and SopB secretion assay in CP327 complemented with p705CRP (C). Immunoblots were also probed with an anti-DnaK antibody as a loading control and to detect signals resulting from bacterial lysis. The average intensity of secreted proteins was quantified and normalized to the intensity of DnaK for WT, CP327 and PQ518 strains (A, lower panel).