MAPK1 and neoplasm: To investigate whether the anti-growth and anti-oncogenic effects of MEK/ERK inhibition are peculiarity of soft tissue-derived tumor cell lines, such as RD, we used IGR39 melanoma-, SW403 colon adenocarcinoma-, PC3 prostate-derived human tumor cell lines, C2C12 and NI3T3 as control untransformed muscle and non-muscle cell lines.