we conclude that part of the low efficiency of tumor production and reduced growth rate of the transformed cells in mice resulted from a combination of ( a ) the paucity of growth factors in interstitial fluid , ( b ) the marked reduction in concentration of essential amino acids encountered by the cells in passing from culture into mice , and ( c ) the fact that cells multiplying in s.c. space do so without benefit of attachment to a solid substratum .
C0007595
growth
C0007634
cells