Previous work with this in vitro model identified Agr quorum-sensing system activation and staphylokinase (Sak) secretion as factors causing spread of bacteria from the abscess community (Guggenberger et al., 2012), but the observed “starburst” phenotype of the ΔarlRS and ΔmgrA mutants was independent from Agr and Sak. The gene discussed is PLK4; the disease is abscess.