(A) SR-1277 (100 nM) decreases the expression of SHH-induced levels of Ccna1, Ccnb1, Ccnd2, Ccne1, Cdkn1a, and Cdkn1b mRNA in GCPs. GCPs were treated with SHH (75 ng/mL) and/or SR-1277 for 24 or 48 h. The mRNA was amplified by qRT-PCR, and fold-change in gene expression was determined by normalizing to GAPDH values relative to control samples. (B) CK1δ knockdown reduces the expression of Ccna1, Ccnb1, Ccnd2, and Ccne1 mRNA levels in the presence of SHH. GCPs were electroporated with two different siRNAs against CK1δ, and the mRNA levels were analyzed after 72 h in vitro. Results shown are the averages of three independent experiments and are represented as the mean ± SEM (*p <0.05, **p <0.001, ***p <0.001, ****p <0.0001).