CCR6 and head and neck squamous cell carcinoma: The heatmap results revealed several chemokines and chemokine receptors that were negatively correlated with the expression of PHLDB2 in HNSCC (Figure 4E,F), specifically CCL4 (r = −0.306, p = 1.25 × 10−12), CCL5 (r = −0.353, p = 8.58 × 10−17), XCL2 (r = −0.417, p < 2.2 × 10−16), CCR5 (r = −0.404, p < 2.2 × 10−16), CCR6 (r = −0.443, p < 2.2 × 10−16), and CXCR6 (r = −0.385, p < 2.2 × 10−16) (Figure S4).