The present invention relates to a composition for inhibiting cell proliferation, suppressing tumour growth, and suppressing expression of cell growth markers in human or animals, characterised in that said composition comprises eurycomanone, or analogues, or derivatives thereof. The composition is extracted from roots or stems of Eurycoma longifolia. The composition may also comprise quassinoid fraction of Eurycoma longifolia extract. The cancer cell growth markers include but not limited to lung cancer tumour markers (hnRNP A2/B1), p53 tumour suppressor protein, prohibitin (PHB), annexin 1 (ANX1), and endoplasmic reticulum protein 28 (ERp28). The inhibition of cell proliferation includes inhibition of metastasis and angiogenesis of cancer. The cell is a cancer cell including but not limited to lung cancer cell.