PLCD1 and neoplasm: In contrast, tumor‐suppressive circRNAs, specifically circ‐0004018, circ‐0072309, circ‐0000520, and circ‐PLCD1, can diminish PI3K/AKT by upregulating PTEN or downregulating IGF1R, resulting in decreased proliferation, invasion, and increased responsiveness to treatments such as herceptin.