The antiproliferative properties of natural cannabinoids and their derivatives are thoroughly investigated, therefore we examined CBD, CBG and their derivatives (CBD derivatives: 8, 9, 10, 11, 12, 13; CBG derivatives: 16b, 17a, 17b, 19b, 20, 21a) against four different cancer cell lines (MDA-MB-231: a highly aggressive breast cancer cell line; A2780: epithelial ovarian cancer cell line; MCF7: a slow-growing breast cancer cell line; SiHa: derived from squamous cervix carcinoma) in two concentrations (10 and 30 μM). This evidence concerns the gene OPN1MW and breast cancer.