CD4 and gastric adenocarcinoma: Immune infiltration analysis revealed significant associations between PRKD1 expression and immune cell subsets, namely, B cells, CD4+ T cells, macrophages, neutrophils, and dendritic cells in thyroid carcinoma (THCA), stomach adenocarcinoma (STAD), liver hepatocellular carcinoma (LIHC), and kidney renal clear cell carcinoma (KIRC).