Characterization of NclFed1A as fibroblasts. (a) NclFed1A has a normal fibroblast morphology. (b) Cells were positive for HFF-Cellect, a mouse monoclonal antibody derived from mice immunized with human foreskin fibroblasts (scale bar, 50 μm). (c) Cells were positive for the fibroblast marker 5B5 required for triple-helix formation in collagen (scale bar, 50 μm). (d-f) Histograms from flow cytometry showing the proportion of cells positive for (d) CD90, (e) CD166, and (f) CD44. (g) NclFed1A had a normal male karyotype. (h) The doubling time of NclFed1A was 26.7 hours; no significant difference was found between PD0, PSB, MCB, and 10 (PD10) and 28 (PD28) cell doublings from the MCB.