DCs express multiple activators of Arp2/3 complex, of which two have been implicated in maturation-associated changes in actin architecture: Hematopoietic lineage cell-specific protein 1 (HS1), the hematopoietic homolog of cortactin (Huang et al., 2011), and WASp, the protein defective in Wiskott-Aldrich syndrome (Bouma et al., 2007; Bouma et al., 2011; Calle et al., 2004). The gene discussed is HCLS1; the disease is Wiskott-Aldrich syndrome.