cyclic amp levels per mg of cell protein were higher in late-passage ( senescent ) fibroblasts than in early-passage ( young ) fibroblasts both during growth and stationary phase , but , because the protein concentration per unit volume in senescent cells was lower than in young cells , the molar concentrations of intracellular cyclic amp were very similar in the two cell types .
C0016030
fibroblasts
C0007634
cells