LEP and breast cancer: As in the case of the MCF-7 breast cancer cells, it was observed that this antiproliferative effect is due to the sensibility of the cells while being recultured and the immediate administration of leptin; since despite a decrease in the cell population during the first stimulation with leptin (24 h), in the second, there was a small increase in the population with regard to the cells obtained at 24 h of stimulation: for the concentration of 10 ng/mL, an increase of 60%; for 100 ng/mL, an increase of 40%; and for 1000 ng/mL, an increase of 28.33%.