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. 2021 Sep 10;12:5386. doi: 10.1038/s41467-021-25700-6

Fig. 4. Inhibition of CDK4/6 facilitates SP1-mediated CDK6 upregulation.

Fig. 4

a Ribociclib treatment led to CDK6 accumulation in a time-dependent manner in MCF7 and MDA-MB-231 cells. b GSEA analysis showing the enriched and suppressed transcription factors upon ribociclib treatment in MDA-MB-231 cells. The P values were calculated using Kolmogorov-Smirnov tests. c Luciferase reporter assay showing that SP1/p300/CBP complex governs CDK6-promoter driven luciferase expression (n = 4). The P value was calculated by Student’s t-test (two-sided). **P < 0.01. d Luciferase reporter assay showing that the promoter region of -600bp~0 bp of CDK6 is responsible for SP1/p300/CBP-mediated induction of luciferase expression (n = 3). The P values were calculated by Student’s t-test (two-sided). **P < 0.01. e Luciferase reporter assay showing that the conserved GC box in CDK6 promoter region is necessary for SP1/p300/CBP regulation of luciferase expression (n = 6). The P values were calculated by Student’s t-test (two-sided). **P < 0.01. f ChIP analysis showing that SP1 accumulation on the CDK6 promoter region is significantly enriched in the context of CDK4 depletion in MDA-MB-231 cells (n = 3). The P values were calculated by Student’s t-test (two-sided). **P < 0.01. g ChIP-seq analysis showing the overlap of target genes regulated by SP1 and E2F1. h GSAE analysis showing that the E2F target was reduced, while SP1_Q6_01 genes were increased in the context of ribociclib treatment in MDA-MB-231 cells. The P values were calculated using Kolmogorov–Smirnov tests. i Luciferase reporter assay showing that the SP1/p300/CBP complex plays a major role in regulating CDK6 transcription (n = 3). The P values were calculated by Student’s t-test (two-sided). #: no significant difference, **P < 0.01. Data are presented as mean values ± SEM. The relevant raw data and uncropped blots are provided in Source Data.