1) The L-O cell absolutely required serum for proliferation, but L-N cell grew rapidly in serum free medium.
2) L-N cell cultured in MEM medium with TPB reached high saturation density as in serum containing medium.
3) The growth rate of L-N cell in serum free medium was dependent on initial density of cell population just before logarithmic growing phase.
4) L-N cell rounded cell cycle from G-1 phase to S phase 4 hours faster than L-O cell.
