Figure 1From: Roles of Polo-like kinase 3 in suppressing tumor angiogenesis Domain structures of human Plks. All Plks have a highly conserved kinase domain and a polo box domain (PBD). Plk 1-3 and 5 have two polo boxes (PB) while Plk4 has one discernable PB. Human Plk5 has a truncated kinase domain.Back to article page