Stratification by RAC1 expression quartiles revealed that higher RAC1 levels were associated with distinct immunogenomic landscapes, including elevated lymphocyte infiltration scores, increased TCR and BCR diversity, greater tumor mutation and neoantigen loads, higher somatic copy‐number alteration burden, and increased intratumor heterogeneity, alongside reduced tumor purity (Figure 7B). The gene discussed is BCR; the disease is neoplasm.