CDK5R1 3'-UTR fragments differently affect reporter gene expression. A) Schematic representation of luciferase constructs carrying fragments of the 3'-UTR of CDK5R1. The pGL4.71P control construct contained no CDK5R1 UTR sequences. The chimeric constructs were created by cloning C1, C2, C3, C4, C5 and C6 3'-UTR fragments downstream of the Renilla luciferase gene. B) Luciferase activity of the six pGL4.71P- constructs in SK-N-BE, SH-SY5Y, HEK-293 and MCF-7 cell lines. Cells, transiently co-transfected with the pGL4.71P- constructs (Renilla luciferase) and the pGL3 (Firefly luciferase) vector were harvested 24 hours post-transfection. Luciferase activity of the chimeric constructs normalized as described, is represented as a percentage of the activity observed in cells transfected with pGL4.71P (defined as 100%). Means ± s.d. luciferase values were obtained from at least four independent experiments (* p < 0.01 compared with the corresponding pGL4.71P value). C) mRNA levels of the chimeric transcripts. Total RNA was extracted from the cells harvested 24 hours post-transfection, and the reporter gene mRNA levels were analyzed by RealTime PCR. mRNA levels of the chimeric reporter gene normalized as described, are represented as a percentage of the mRNA levels observed in cells transfected with pGL4.71P (defined as 100%). Means ± s.d. luciferase mRNA values were obtained from at least three independent experiments (* p < 0.01 compared with the corresponding pGL4.71P value).