ARPC1B and cancer: Meanwhile, conserved Arp2/3 subunits exhibit divergent functions: ARPC5 deficiency causes severe systemic inflammation in humans (Sindram et al., 2023), but its homolog ARPC5L knockout has no obvious immune phenotype (Abella et al., 2016); ARPC1A drives cancer cell proliferation (Zhou et al., 2025), while ARPC1B is critical for B cell tonic signaling and platelet function (Randzavola et al., 2019; Leung et al., 2021).