Introduction 2007 2007 2007 1987 1982 1985 1987 1985 1988 1991 1994 1995 1983 1987 1988) 1995 1995 2005 2006 2007 2006 2002 Clathrin-independent endocytosis: expansion of the field 2007 1 2007 2007 2006 2001 2005 1995 2006 1983 1985 1987 1985 2006 2006 2007 Fig. 1 a b  Internalization of membrane components and ligands by endocytosis thus have different requirements when it comes to dependency of dynamin, caveolin, flotillin, and small GTPases, and in addition, cholesterol and other specific lipids play a role (see below). To which extent the different endocytic mechanisms vary depending on cell type, growth conditions and the extent of cell polarization is to a large extent not known, and has to be addressed in future studies. It should be stressed that most of our knowledge about clathrin-independent endocytic mechanisms derives from cells in culture. 2005 2007 2007 1 1 2000 1998 Membrane lipids required for clathrin-independent endocytosis 2006 2006 2007 2007 2006 2007 2005 2006 2007 2007 2007 2002 2007 2007 1999 1999 2004 2 2007 1999 1999 Fig. 2 2001 n  Role of actin in endocytosis 2002 2005 2006 2006 2006 2007 2007 2000 Macropinocytosis  1992 1 2007 2007 2007 2007 2006 2006 2006 2006 RhoA-, cdc42- and CTBP3/BARS-dependent uptake 2007 1 2007 2001 2006 1999 2006 2007 2005 Arf6-dependent uptake  1997 2001 2002 2004 1997 2003 2007 2007 2007 2005 2007 2005 2005 2006 2006 2007 Caveolae and endocytosis 3 3 4 2001 2001 2001 2005 2005 Fig. 3 a Cav Cp b c d Bars   Fig. 4 a–d a) arrowheads arrows open arrow asterisk b–d arrows asterisks a) Bar  2002 2005 2006 2005 2007 2003 2004 2005 2006 2005 2007 2002 2005 2000 2005 2002 2002 1994 2002 2007 2002 2005 2003 2001 2002) 2005 2005 2003 2007 2006 2003 2007 Regulation of endocytosis in polarized epithelial cells 2007 1978 2005 1994 1995 2000 2000 1996 1994 1987 1994 2005 1994 1995 2000 2000 1996 2001