BCL2 and pituitary tumor: However, Soini et al[51] have also reported a higher apoptotic index in malignant tumors, which is consistent with the findings of Kulig et al.[39] In many cancers, apoptosis and proliferation are linked, although the underlying mechanisms remain unknown.[51] Therefore, it is currently unclear whether Bcl-2 proteins can be used as biological markers of malignant transformation in PCs, and the correlation between proliferation and apoptosis in pituitary neoplasms should be further investigated.