CDK4 and colorectal carcinoma: To examine the efficacy of dual blockade of CDK4/6 and MEK on KRAS mutant CRC cells, cell growth and colony formation were determined after treatment with the MEK inhibitor MEK162 and the CDK4/6 inhibitor palbociclib, using clinically relevant doses of palbociclib [28, 29] and doses optimized to each cell line to maximally display contrast of cell growth between monotherapies and combination therapy (See Supplementary Table S1 and Figure S1).