WEE1 and osteosarcoma: Furthermore, VD3 can instigate a rapid influx of Ca2+ from the extracellular space through voltage-independent channels in rat osteosarcoma cells (48), trigger the release of Ca2+ from intracellular stores in osteoblasts (46), and activate protein kinase pathways, which may be either Ca2+-dependent or -independent (46, 47).