Figure 4.

Effects of palbociclib, paclitaxel, and sequential combination therapy on cell growth and cell cycle progression of parental (T47D_PAR) and paclitaxel-resistant T47D cells (T47D_PAC). A: Cells were treated with DMSO (control; C) for 6 days; 2 nM paclitaxel (PAC) for 6 days; 500 nM palbociclib (PD) for 7 days; 500 nM palbociclib for 1 day followed by addition of 2 nM paclitaxel for 6 days; 500 nM palbociclib for 1 day followed by addition of drug-free medium (free) or 2 nM paclitaxel for 6 days after PD washout (W). Cell counting was performed and the results for each treatment were presented as percentages of control. ****p < 0.0001; **p < 0.01. B: Cells were treated with DMSO (control; C) for up to 24 hours; 4 nM paclitaxel for up to 24 hours; 500 nM palbociclib for up to 48 hours; 500 nM palbociclib for 24 hours followed by 4 nM paclitaxel for 24 hours; 500 nM palbociclib for 24 hours followed by drug-free medium or 4nM paclitaxel for 24 hours after PD washout. The effects of each treatment on cell cycle distribution and cell death (sub-G1) were evaluated by flow cytometry.