STAT3 and neoplasm: However, Guo et al., using the model of hepatocellular carcinoma, have shown that by increasing the cyclin dependent kinase inhibitor p27kip1, calcitriol reduces the secretion of pro-inflammatory cytokines and consequently inhibits signal transducer and activator of transcription 3 (STAT3) signaling activation, which eventually suppresses tumor development in mice [14].