NUCLEOLIN and cancer: Its nucleic acid sequence is rich in guanine, which easily forms a quadruplex structure.613 This unique structure not only resists nuclease degradation but also inhibits the proliferation of cancer cells by specifically targeting nucleolin.614,615 In a phase I clinical trial involving patients with advanced cancer (NCT00881244), AS1411 was well tolerated after six months of treatment, with no adverse reactions observed, except in patients with renal cell carcinoma.