Table 1.

Lapatinib induces G0-G1 arrest in the presence of IGF-I

SamplePercentage of cells per cycle phase
G0-G1SG2-M
Parental, serum-starved control77.46 ± 0.298.8 ± 0.1312.0 ± 0.05
Parental, IGF-I + lapatinib88.83 ± 0.061.6 ± 0.044.9 ± 0.12
Pool 2, serum-starved control66.87 ± 0.088.7 ± 0.3121.68 ± 0.43
Pool 2, IGF-I + lapatinib80.41 ± 0.093.0 ± 0.0313.33 ± 0.1
Clone 3, serum-starved control64.29 ± 0.3413.55 ± 0.3520.29 ± 0.08
Clone 3, IGF-I + lapatinib75.57 ± 4.432.22 ± 0.0514.27 ± 0.45
  • NOTE: Parental, pool 2, and clone 3 cells were serum starved overnight and then either fixed without further treatment or incubated with IGF-I (100 ng/mL) and lapatinib (1 μmol/L) for 24 h before fixation. Cells were stained with propidium iodide, and DNA content was examined by flow cytometric cell cycle analysis (fluorescence-activated cell sorting). Percentages of cells in each cell cycle phase are shown with SD between duplicate cultures per group. Increased percentages of cells in G0-G1 and reduced percentages in S phase indicate that lapatinib induces cell cycle arrest at G0-G1 even in the presence of exogenously added IGF-I.