34. Which of the following statements about mitosis and stem cells is/are CORRECT?
(A) Most tissues contain various numbers of stem cells as a source of cell renewal, including the nervoussystem.
(B) iPSCs (induced pluripotent stemn cells) can be formed from somatic cells by expression of combinationsof key transcription factors, including KLF4, Sox2, Oct4 and Myc.
(C) Animal cloning establishes that cell differen entiation can be reversed.
(D) Symmetric cell division increases cell diversity, and asymmetric cell division expands cell number.
(E) Positioning of mitotic spindle, which determines the plane of cell division, could be regulated by extrinsicfactors