Fig. 6. Drosophila signal transduction pathways involved in immunity and their contribution to crystal cell rupture. Mutants in the factors that are shown in red were tested, mutants that show defects crystal cell rupture are also underlined (see Brennan and Anderson, 2004; Delaney et al., 2006). In addition to regulating the early phase of transcriptional immune and stress responses (Boutros et al., 2002; Park et al., 2004), Bsk acts in a transcription-independent way downstream of Rho GTPases and upstream of cytoskeletal regulators. Dl/Dif, dorsal/dorsal-related immunity factor; GNBP1, gram-negative binding protein 1; IMD, immune deficiency; PGRP-LC, peptidoglycan recognition protein LC; PGRP-LE, peptidoglycan recognition protein LE; PGRP-SA, peptidoglycan recognition protein SA; TAK, HIV Tat-associated kinase; Tl, toll.