21.   Leading scientists note, however, that once they produce such an embryo cell, by cloning, that cell need not become a new human being.

22.   PV cells become more efficient with each new generation of technology, which already makes these products economically feasible.

23.   Probably four or five separate genes must be knocked out before a normal cell becomes a fully developed tumor cell.

24.   Scientists believe that breast cells become cancerous after several genes in those cells become damaged or malfunction.

25.   Slowly, the genetically altered cells will become the predominant population of cells in her bone marrow.

26.   The cells become malignant.

27.   The company said the hybrid cells quickly became more humanlike, as the human nucleus took control and displaced cow proteins with human proteins.

28.   The company said the hybrid cell quickly became more human-like as the human nucleus took control and displaced cow proteins with human proteins.

29.   The gene seems to play a pivotal role in suppressing malignant changes, and when it is inactivated the breast cells become much more prone to cancer.

30.   The new terrorist cells became a huge intelligence headache, since many carried out one attack, dissolved, and reformed with new members across the porous European borders.