You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Anti-proliferative effect of (19Z)-halichondramide, a novel marine macrolide isolated from the sponge Chondrosia corticata, is associated with G2/M cell cycle arrest and suppression of mTOR signaling in human lung cancer cells. Five oxazole-containing macrolides isolated from the marine sponge Chondrosia corticata were evaluated for their anti-proliferative activity in a panel of human solid cancer cell lines. (19Z)-Halichondramide ((19Z)-HCA), a novel trisoxazole-containing macrolide, exhibited the highest potency among the macrolides, with IC50 values in the submicro-molar ranges. Prompted by the high potency of growth inhibition of cancer cells, we investigated the mechanism of action of the anti-proliferative activity of (19Z)-HCA in human A549 lung cancer cells. (19Z)-HCA induced cell cycle arrest in the G2/M phase, and this event was highly correlated with the expression of checkpoint proteins, including the up-regulation of p53 and GADD45α and the down-regulation of cyclin B1, cyclin A, CDC2, and CDC25C. In addition, the growth inhibition by (19Z)-HCA was associated with the suppression of mTOR and its downstream effector molecules 4EBP1 and p70S6K. The modulation of mTOR signaling by (19Z)-HCA was found to be mediated by the regulation of upstream proteins, including the down-regulation of Akt and p38 MAPK and the up-regulation of AMPK. These data suggest the potential of (19Z)-HCA to serve as a candidate for cancer chemotherapeutic agents derived from marine organisms by virtue of arresting the cell cycle in the G2/M phase and the modulation of mTOR/AMPK signaling pathways.
{"Chemical": ["oxazole", "(19Z)-Halichondramide", "(19Z)-halichondramide", "(19Z)-HCA", "trisoxazole"]}