BCL2 and cancer: To measure the mRNA expression level of apoptotic (p53 and Bcl2) and mitochondrial NADH dehydrogenase 3 (ND3) genes in the control and Y2O3NPs -treated A-431 cancer cells using qRT-PCR, whole RNA was first extracted from A-431 cancer cells using the GeneJET RNA Purification Kit from Thermo Fisher Scientific Company (USA), and and then the extracted RNA was converted to complementary DNA (cDNA) using the cDNA Reverse Transcription Kit from Applied Biosystems (Foster City, CA, USA).