Moreover, in synchronized human U2OS osteosarcoma cells, which, in contrast to HeLa and HT1080 cells, possess a functional circadian oscillator, GAPVD1 was rhythmically associated with CSNK1D, and the strength of this interaction mirrored the binding of PER2 to CSNK1D (Figure 5E). This evidence concerns the gene PER2 and osteosarcoma.