CTLA4 and neoplasm: This interaction might result in delivering CTLA-4-mediated negative signals into tumor cells leading to inhibition of their proliferation rate and/or induction of apoptotic cell death (Contardi et al., 3005) Also, agreed with Zhao et al (2018) who demonstrated that persistent expression of CTLA-4 on tumors contributed to the progression of both hematological and solid tumors, which produced inhibitory signals to weaken the immune response.