\documentclass[12pt]{article}
\usepackage{graphicx}% nur für demo
\pagestyle{empty}
\parindent=0pt
\usepackage{colortbl}
\definecolor{myCol}{rgb}{1,0.95,0.95}
\usepackage{array}
\makeatletter
\def\markCell{\@ifnextchar[{\@markCelli}{\@markCellii}}
\def\@markCelli[#1]#2#3{
	\hspace{0pt}\makebox[0pt][l]{%
		\raisebox{-0.25\height}{\huge\textcolor[#1]{#2}{#3}}}%
}
\def\@markCellii#1#2{
	\hspace{0pt}\makebox[0pt][l]{%
		\raisebox{-0.25\height}{\huge\textcolor{#1}{#2}}}%
}
\makeatother

\begin{document}
\scalebox{3}{% nur demo
\begin{tabular}{c>{\columncolor{myCol}}cc}
\markCell{blue}{A1}blah
  & B1
  & \markCell[gray]{0.9}{C1}Carole\\
A2
  & \markCell[gray]{0.75}{B2}blub
  & \multicolumn{1}{>{\columncolor{red}}c}{C2}\\
\rowcolor[gray]{0.95}A3
  & B3
  & \markCell[gray]{0.9}{C3}blubber\\
A & B & C
\end{tabular}%
}
\end{document}