miR-335 appears to control growth by blocking cell proliferation by targeting certain genes; e.g., RASA1 in rat epididymal development [39], SP1 and Bcl-w in non-small cell lung cancer [8], SOX4 and TNC in breast cancer [2], ROCK1, MAPK1, and LRG1 in neuroblastoma [40], and Rb1 in U2OS osteosarcoma cells [41]. The gene discussed is MAPK1; the disease is breast cancer.