CDKN1A and osteosarcoma: In human osteosarcoma cells, after 24 h stimulation with 1,25(OH)D 100 nM we observed a significant upregulation of OCN, CDKN1A, CaBP9K and CYP24A1, which was blunted upon co-incubation with PFOA, with the exception of CaBP-9 K.