Changes in the expression of cyclins, CDKs, CDKs inhibitors. Changes in the expression of cyclins, CDKs, CDKs inhibitors were quantified by Western blot in HT-29 cells treated with 5-FU for 48 h after 12-h pretreatment with CQ. Treatment of HT-29 cells with 5-FU alone resulted in decreased expression of cyclin D1, p21Cip1 and p27Kip1, time-dependently. In addition, 5-FU treatment resulted in accumulation of CDK2. Pre-treatment of cells with CQ resulted in inhibition of 5-FU-induced down-regulation of p21Cip1 and p27Kip1 expressions and, on the other hand, decreased the expression of CDK2. The expressions of cyclin E, CDK4 and CDK6 were not affected by 5-FU and/or CQ treatments. The expression levels of cyclins, CDKs, and CDKs inhibitors are expressed as the density measured by the Image J software, standardized by the density of β-actin.