GDF15 and oral cavity squamous cell carcinoma: Some studies have demonstrated that conditioned media from M1 macrophages can enhance the migration and invasion of neoplastic cells, including oral squamous cell carcinoma, via mechanisms involving GDF15 and ErbB2 phosphorylation.43 Conversely, research on other cancer, such as esophageal squamous cell carcinoma, indicates that M1 macrophages inhibit invasion and migration, which is associated with improved patient prognosis.44 This apparent paradox highlights that M1 macrophage activity is context-dependent and varies with the specific tumor microenvironment.